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By Dennis Ayling, August 2025

Ideally, the London Borough of Barnet should function as a beautiful biological bridge between the green belt Hertfordshire countryside and the Inner London boroughs. Is it falling down? No, not quite, but it is becoming increasingly shaky. Although it is a multi-lane bridge, the various lanes are gradually getting disrupted, potentially rendering them ineffectual. If just one span of a bridge lane is undermined, somewhere along its length, then the whole structure is compromised. Take, for example, the Edgware branch of the Northern line, long-recognised as a fortuitous north-south green lane for flora and fauna. Its open, rural-style station platforms, like the one at Burnt Oak, are of little hindrance to the passage of wildlife. 

An open, rural-style platform at Burnt Oak Station.

The new huge station at Colindale, bestriding the railway and coupled to the road bridge, is a different matter. This imposing building may look bright and airy at surface level but beneath, on the platforms, it is a dingy and depressing experience for train passengers. Furthermore, the new track-straddling station disrupts this green corridor, especially now that Barnet has approved two massive tower blocks contiguous with the enormous new station building. One of which is insanely planned to be over 20 stories high! Absurdly, this is said by the architects to act as a marker for the location of Colindale Underground Station: https://constructing-london.com/colindale-station-and-new-homes/. Foregoing this vanity skyscraper would have allowed a similar station entrance to be sensibly sited to the west of the railway track instead of spanning it. Green foresight would have left open, rural-style platforms at Colindale, supportive of the Edgware line's status as a wildlife corridor.

Compare the former brief bridge interruption (i.e. the two bridge arches, opposite the commuters, at the far end) to the full length interruption now.

Nobody disputes the need for increased housing provision, but the manic rush to maximise density on every square metre, as in the case of Colindale Station with its planned adjoining oppressive towers, is calamitously short-sighted. Both the wildlife and human populations will lose out in the long term, especially with climate change bearing down on us.

To be fair, the current Barnet Council is making a more than a decent effort at tackling the twin crises of biodiversity loss and climate change. It has created major wildlife habitat improvements, serving as flood alleviation areas, in both Silkstream Park and Watling Park. Barnet has many inspiring small initiatives too, like encouraging multiple "buzz stops" ["…portable pots planted with pollinator-friendly herbs and flowers that people can situate in their gardens and balconies thus providing nectar rich pathways for insects."] throughout the borough. The Borough's planning process encourages the inclusion of swift nesting sites on new buildings. A tiny forest, alongside the Mutton Brook in Finchley, had 1800 trees added to it this year. Some excellent environmental and sustainable initiatives are certainly underway throughout Barnet, overseen by its full-time biodiversity officer.

So what is the problem then? Well, biological bridge lanes, even with brilliant bits, need more. Uninterrupted continuity is critical for sustaining biodiversity, facilitating gene flow, and enabling species to adapt to environmental changes. Several super spans (e.g the Silkstream and Watling wetland habitats) are magnificent but any weak or missing spans hinders or stops the biological traffic between the outer green belt and the inner London boroughs. The south-flowing Silk Stream is beautifully enhanced near Burnt Oak's Watling Estate. In my view, the estate now rivals the more celebrated Hampstead Garden Suburb. However, downstream, beyond Rushgrove Park, this watercourse goes downhill – and not just topographically. Along this final stretch, with buildings along both banks, it is not possible to walk alongside the stream. Its environmental quality deteriorates further as it passes through an industrial zone in Hendon. Even the wooded area, just prior to it flowing into the Brent Reservoir (Welsh Harp), is a litter-strewn, neglected mess. Truly shocking, given this huge reservoir is a government-recognised Site of Special Scientific Interest (SSSI).

There is another stream of water running the length of the borough, also flowing into the Brent Reservoir, called the Dollis Brook. It has a more consistent green environmental quality along its entire length, compared to the Silk Stream. However, at the southern end of Barnet, the Dollis Brook combines with the Mutton Brook to form the River Brent. Here is where everything goes disastrously wrong, in terms of the now river serving as a wildlife corridor and green walkway. This pitiful initial section of the River Brent flows west, encased in an ecologically destitute concrete conduit. Like the Silk Stream, it too is an ugly, rubbish-strewn mess where it flows into the Brent Reservoir, SSSI. I have previously described how this environmental eyesore and ecological disaster could be totally transformed. This link proposes how Barnet's section of the River Brent could be beautifully restored: https://www.barnetclimate.org.uk/2024/06/retail-nature/ . It would become a major wildlife wetland nature reserve and flood alleviation asset at the southern, environmentally-impoverished end of the borough.

This photograph shows the barren ecological state of Barnet's stretch of the River Brent at Brent Cross.

This picture illustrates how the river at Brent Cross could be amazingly transformed to a natural state. It is a photograph of the wetland created by Barnet in Silkstream Park. The same could be done at Brent Cross on a much bigger scale. This would massively enrich the southern end of Barnet, which is ecologically impoverished compared to the rest of the borough. Simultaneously, it would restore the wildlife corridor from the greenbelt to the Inner London boroughs.

Surely, the aim should be to view the two water courses (Silk Stream and Dollis Brook) plus the two branches of the Northern line (Edgware and High Barnet) as four north-south wildlife corridor lanes that ought to be individually strengthened rather than fragmented. Furthermore, as the two rail tracks run close to one of each of these two water courses, they should be viewed as two sets of ecological complementary pairs. The Silk Steam and the Edgware branch of the Northern line should always be looked at in unison, as should the Dollis Brook and the High Barnet branch of the Northern line. One important feature of this overarching environmental approach must be the retention of open, rural-style platforms on both branches of the Northern line. There has been talk of "upgrading" other Northern line stations, although certainly not for wildlife!

Open, rural-style stations do not obstruct the Northern Line rail track wildlife corridor.

Another essential aspect of maintaining Barnet's biological bridge is the ecological enhancement of parks, playing fields and even streets alongside the two branch lines and the two watercourses. For example, Hendon Park adjacent to the Edgware branch line could contribute to the rail track wildlife corridor as well as the restoration of the River Brent at Brent Cross. The aim should be to ecologically enrich and diversify the habitats within all these scattered green spaces and to link them together, including with street tree corridors.

We must recognise that two adjacent wildlife corridors, one a water course and the other a rail track, are more potent together than just one or the other. Barnet's north-south biological bridge has at least four lanes – two watercourses and two rail tracks. It also has other scattered green spaces that should be linked to these by street tree corridors and more. For example, pavement level planting, street bioswales, layered hedges along boundaries, climbing plants to create green walls, and green roofs on buildings. All these ecologically upgrade and diversify an urban environment as well as make it more climate resilient.

To summarise, in serving as a biological bridge, Barnet faces a variety of threats along its length. Undoubtedly, it has some stunning spans, but other parts are seriously damaged. Most notably, Barnet's section of the River Brent was decimated decades ago. How tragic that, just at the point of delivering biodiversity to the Inner London boroughs, Barnet's biological bridge is close to collapse. Here, one of its principal lanes exiting the borough is reduced to a poor, derelict ditch, thereby unfairly denying the residents in the southern section of Barnet the green environment and rich wildlife enjoyed by those at the affluent north end of the borough.

In assessing the ecological soundness of Barnet's biological bridge, it's not a matter of one or even two weak spots. Rather, the issue is the gradual accumulation of them, especially where housing development is now taking place. Then there are long-term existing weaknesses towards the southern end of the Borough, just at the very point where Barnet should be bestowing biodiversity upon the Inner London Boroughs. Here is where the biological bridge is currently at its most precarious. Brent Cross need not be an area of ecological dereliction, as it is now. It should, and could, be the Brent Cross(ing) point for wildlife. To the Inner London boroughs, it would be lauded as "Biodiversity Cross".

Barnet's north-south biological bridge divides at the borough's southern tip. The bridge's watercourse lanes turn west towards the London Borough of Brent. These lanes, the Silk Stream and the River Brent, flow into the Brent Reservoir and the Borough of Brent. Perhaps it is worth noting here that Brent has "higher levels of poverty and deprivation compared to the London and England averages". There is an established greenwalk and wildlife corridor from Totteridge heading south along the Dollis Brook to Brent Park. Here the Dollis Brook meets the Mutton Brook to give rise to the River Brent. Within a matter of a few hundred metres of this confluence, the greenwalk abruptly ends and the river totally loses its ecological identity, becoming a brutal concrete drainage ditch at Brent Cross. It remains in this sterile state, polluted with litter and sometimes sewage, for a long stretch parallel to Brent Cross Shopping Centre's Prince Charles Avenue. How ironic, when we recall our head of state's lifetime dedication to multiple green issues, including tackling the biodiversity and climate crises now overtaking us.

I have already shown how this environmentally-unsustainable urban disaster could be rectified in my Brent River restoration proposal, referred to earlier in this piece. Enhancing parks and other existing green spaces is of course environmentally desirable and ecologically very valuable. Such projects can significantly support biodiversity and improve climate resilience. However, to tackle the concrete and asphalt covering most of Brent Cross is of a totally different order. It requires vision and demands courage to take on such a radical transformation of the urban environment. The promotional push selling "park living" at the new Brent Cross Town is just that, and that is fine. Nobody objects to some measure of relief created by a degree of green landscaping among multiple massive tower blocks. However, it is not the lush natural environment enjoyed by residents at the northern end of Barnet. Fully restoring a meandering River Brent with a surrounding wood and water meadows, in unison with greening the Shopping Centre, would truly re-ruralise the southern end of Barnet. "Biodiversity Cross" would then serve to enrich the Inner London boroughs with flora and fauna via Barnet's beautifully restored biological bridge.

Clearly, the west-headed wildlife lanes at the southern end of Barnet's biological bridge are in need of radical repair and restoration. However, there is one substantially intact bridge lane branching east towards the Inner London Borough of Camden. As fate would have it, this is a wealthy borough. This largely undamaged bridge lane runs the length of Barnet, consisting of the Dollis Brook and, for part of its length, the adjacent Barnet branch of the Northern line.  A wildlife corridor and greenwalk that extends as far as the North Circular Road. Here, ducking beneath the carriageway, this bridge lane turns east along Mutton Brook, just south of and parallel to the North Circular Road. On reaching Hampstead Garden Suburb and progressing through Little Wood and Big Wood, Barnet's final span of this biological bridge lane is the Hampstead Heath Extension. Encouragingly, Barnet's biodiversity officer oversaw the expansion of a new wood alongside the Mutton Brook earlier this year. In my view, more needs to be done in Hampstead Garden Suburb to intensify tree corridors along its roads leading to the Hampstead Heath Extension. I made much the same suggestion to Camden Council, in relation to its residential Belsize Park area, which sits between Hampstead Heath and Primrose Hill in their borough: https://www.barnetclimate.org.uk/2025/05/primrose-hampstead/

This Camden-headed, continuous and largely ecologically consistent bridge lane is to Barnet's credit. It runs from London's green belt, across the north-south length of Barnet, then heads east and finally south to Hampstead Heath. This vital element of Barnet's biological bridge is the initial section of a green walkway and wildlife corridor, now mostly in place, that stretches from Totteridge to the Thames. Serious attention now needs to be focused on the bridge lanes heading west towards Brent, both to facilitate the passage of wildlife to Inner London boroughs and to re-green this area of Barnet, making it more resilient to climate-related heatwaves and flooding already happening with increasing frequency and intensity.

Like many others, I do weekly voluntary work on London's rivers, canals, green walkways, and the like. The tasks vary, from planting trees and hedges to monitoring water pollutants. Sometimes, I am dragging large items out of our watercourses, including shopping trolleys and electric bikes. At other times, I am simply litter-picking, though concentrating specifically on plastics. My motivation is not to 'Keep Britain Tidy', noble as that may be. Rather, I am trying to limit ocean pollution. Yes, not everyone realises what an extraordinary amount of Barnet's dropped plastic bottles and bags gets carried downstream. Barnet's watercourses propel the increasingly fragmented plastic down to the River Thames where it is eventually carried out to sea. It comes as a big shock to many residents that the London Borough of Barnet is adding microplastic to our oceans.

Environmentally, there is much to do on many fronts. Resident volunteers can do a lot to help, but there are major environmental tasks only our local and national government can address. Clearly, Barnet Council is an eco-friendly governing body. It is particularly fortunate in having some outstanding ecological assets at the north end of its borough. I raised my young family at Monken Hadley with Hadley Green, King George's Fields, Hadley Common and Hadley Woods just a stroll from our tiny one-bedroom cottage. As a young teacher, I had previously lived near Brent Cross, confined between the constantly busy North Circular and Great North Way roads. Here, at Brent Cross, is where Barnet Council's values, vision and courage is called on. Virtually daily, we are being given new insights into the multiple and profoundly serious climate-related environmental issues already threatening us. The time to tinker, however well-meaning – like my personal efforts to hold back the tide of ocean-bound plastics – are numbered. Radical, super-scale initiatives must be urgently implemented by a Barnet Council that is, hopefully, not only environmentally informed but is also truly insightful about our planet's perilous future. Instead of the current gradual undermining of Barnet's biological bridge, it should hurriedly be built back better, especially at its southern end. Yes, housing development is a priority, but so is surviving climate change and adapting to the extreme temperatures and frequent, catastrophic flooding it brings. Urgently attending to the repair and maintenance of Barnet's biological bridge lanes will not only be a massive ecological benefit to the whole of Barnet, but it will also assist the Inner London boroughs in addressing the now enveloping climate and biodiversity crises too. 

Barnet's biological bridge lanes – rail tracks and water courses (the latter feeding the Brent Reservoir, SSSI)

Finally, let us consider the much wider imperatives of fixing Barnet's biological bridge, especially where it was biologically butchered by botched town planning half a century ago. Clearly, the complex of road intersections at Brent Cross have become a transport necessity. However, it does not follow that they have to impose ecological dereliction on the surrounding area. Think for a moment of our national motorway verges. These strips of land, adjacent to busy six-lane carriageways of fast-moving traffic, have become wildlife corridors: https://theecologist.org/2024/aug/15/road-verges-can-save-britains-biodiversity. The traffic passing through Brent Cross and over its flyovers could be screened visually, and for noise, by a dense band of trees. Remember, too, that we are gradually advancing towards quieter, non-polluting electric cars and buses. I put my long-standing proposal for the twin objectives of river conduit enhancement and vital climate resilience measures at Brent Cross online in 2022. In that proposal, I advocated using three Barnet borough owned car parks to create a wood and wetland for flood alleviation purposes and heat wave mitigation. Given that the climate and biodiversity crises have alarmingly intensified and swiftly accelerated since then, I felt compelled to go further. We must urgently and vigorously push ahead to meet these twin global crises. A complete restoration of the River Brent, instead of just an improvement of its existing concrete channel, is now required. It would set an inspiring new precedent for urban adjustment to future city life, taking into account the dangerous health risks posed by climate change.

Although ecologically enhancing our fragmented urban green areas is valuable, it is far from sufficient since the climate in the UK has already altered in severity: https://www.bbc.com/news/articles/c74w1gyd7mko. Unfortunately, such green space efforts amount to tinkering at a political level, given the still unacknowledged enormity of what is bearing down on our world. We have to wisely and creatively adapt the built urban environment to face the detrimental consequences of global warming. To achieve climate resilience and liveability the latest research advises that urban greening needs to be nature based and to utilize green-blue-grey infrastructure: https://www.frontiersin.org/journals/sustainable-cities/articles/10.3389/frsc.2025.1595280/full. I recognise that some of the concrete and tarmac at Brent Cross has to remain for transport purposes, yet it could, with scientific-based vision, be radically and uniquely transformed. At a stroke, such a novel paradigm would re-ruralise the blighted southern end of Barnet. If it were enacted, it would undoubtedly capture national and  perhaps international attention as a revolutionary new paradigm for urban adaptation to both climate change and biodiversity loss. What a momentous contribution from UK leadership that would be in addressing the existential danger posed by these twin crises.

I have said many times that I believe Barnet, under its new council, could be a national and quite possibly a world leader in showing the way to develop urban climate resilience and biodiversity restoration at one of London's most daunting and challenging city locations. If Barnet were to apply a nature based solution (NbS) utilizing green-blue-grey infrastructure (GBGI) as I have suggested, this multiplex of road intersections, which includes three flyovers, could be transposed from a hideous urban nightmare to a beautiful environmental dream. I urge Barnet to heed the latest research, to be daring, original and visionary for the future of all life on planet Earth.

Dennis Ayling

Dedicated to Julian, on whom I rehearsed my outdoor parenting skills