National Highways plans for Wisley interchange

Update on National Highways’ M25/A3 plans

View of Lime trees by the A3

Last updated: May 2022

On 12 May 2022, the Secretary of State for Transport granted approval for the M25 Junction 10/A3 Wisley Interchange Development Consent Order.

We are naturally disappointed with the decision. We have engaged constructively from the outset of this process, including producing a deliverable alternative scheme to ensure safer journeys, protect the local environment and irreplaceable woodland and wildlife, and safeguard the future of RHS Garden Wisley.

While this is not the outcome we have long campaigned for, we will now fully consider the detail of the decision. In the meantime, we will continue to liaise with National Highways and others to seek further improvements to the strategic and local road network that will be needed in coming years to minimise disruption for the millions of visitors to our world-class and much-loved garden.

As a member-driven charity, we also want to thank all our members and the local community who supported the RHS in our campaign including through our petition. The petition was a powerful statement on the importance of RHS Garden Wisley and the difference it makes to the local community, but also the national relevance of the garden and the future of horticulture.

We will continue to provide regular updates and will work tirelessly to minimise disruption for those wishing to visit the garden. National Highways will provide regular updates on their website.

​Background story: Why we took action

Back in 2018, we launched a campaign to save Wisley’s trees and more than 134,000 of you signed our petition calling for our objections to be listened to. The petition was a powerful statement on the importance of RHS Garden Wisley and the difference it makes to the local community, but also the national relevance of the garden and the future of horticulture. We cannot thank you enough for your support, but sadly, while the ‘garden grab’ plans were changed, the proposals that remained still caused many critical concerns for the future of Wisley.

The threat to our environment

The impact of Highways England’s earlier proposals would have placed 44 trees along our boundary with the A3 at risk. The plans that were being signed off by the Secretary of State would have seen 17 Grade II Heritage Trees being cut down. It  would also have seen 27 trees, including North American redwood species (Sequioadendron giganteum) and 5 Grade II* Heritage Trees being put at risk because the development could have adversely affected the health of the trees by undermining root strength. Anyone who has seen these magnificent trees in person will tell you of the awe that they bring.
The environmental harms of the proposal may have gone much further than our trees and the future of our garden. Highways England had failed to correctly assess the impacts of the unnecessary extra mileage and the resulting pollution of their scheme on the Thames Basin Heath Special Protection Area. This was important because an RHS Alternative Scheme was provided to Highways England, which reduced the impact on the local villages, and the heathland surrounding the garden. By failing to take account of this fact, we were deeply concerned that our environment could be unnecessarily being damaged for the future.

The threat to the RHS

The Highways England’s scheme would have seen those wishing to visit the garden having to pass the garden up to four times and then have to negotiate a new junction twice. We used this information, and expert advice, to calculate the costs to the RHS of these delays. We learnt that this could have seen a reduction in our income of an estimated £6.6 million during the construction period alone. The reduction in income the RHS would face over the subsequent 10-year operational phase would total £19.2 million.

You might also be interested in...

  • RHS Garden Wisley: From world-class horticulture and advice to imaginative events and great shopping, Wisley has something special for every visitor
  • Ways you can support us: Unleash the power of gardening and support the future of horticulture – we need your help
  • About the RHS: Find out more about us and our aim to inspire everyone to grow

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.