The Challenge
The whole site is covered by root protection zones, and this informed every element of the project and programme. Traditional construction techniques were not permitted; excavations could only take place using an air spade and heavy plant and traditional pipe-based irrigation had to be avoided.
The two new structures – the education centre and gardeners’ hut/WC’s – use steel micro screw piles to float above the ground, thus minimising soil compaction and preventing root damage by not loading the area above protected roots. Detailed air-spade surveys were undertaken to map the full extent of tree roots, and our team were in constant close liaison with Westminster’s tree officer to ensure we complied with their arboricultural and ecological planning condition requirements. During the tender process, our team also took the lead to ensure everyone fully understood the constraints and how these could be overcome.
Over 7,000 people inputted into the public consultation, and many of the prominent residents who adjoin the square also contributed towards the project financially. Sensitive stakeholder engagement was therefore key, including with third parties such as the Royal Marsden Hospital who used the space for a high-profile charity event whilst air-spade work was ongoing. Sequencing was also impacted by the nesting season, by significant site access limitations, and by ensuring the supply of such a large quantity of bulbs at the right moment.
The Outcome
The completed transformation, which opened to the public in July 2026, created an urban garden for everyone to enjoy; its vastly improved biodiversity, public amenities and spaces support wellbeing and encourage Londoners and visitors alike to connect with nature in the heart of the West End.
Planting has been designed to evolve throughout all four seasons, giving visitors something new to experience year-round. Soil health has been significantly improved, with soil aerated across an area twice the size of a Wembley Stadium pitch. This means the soil can now absorb 1.4 million litres of stormwater, equivalent to filling 28 London buses. The Roosevelt Memorial, Eagle Squadrons Monument and 9/11 Memorial have all been carefully retained and enhanced within the new design. Seasonal planting has also been introduced to complement these important spaces, including flowers around the 9/11 Memorial blooming each September.
The new education centre, operated by London Wildlife Trust and funded by The Westminster Foundation, now provides programmes for children and adults focused on biodiversity, climate change and the Square’s rich history.