Following an international design competition in 2019, the Architecture/Landscape Architecture practice Tonkin-Liu was appointed to lead a design team to deliver proposals for the redesign of Grosvenor Square, to RIBA Stage 2.  The design was further developed to detail by BDP.  Nigel Dunnett has been the horticulture/planting design lead for the project. throughout.

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Grosvenor Press Release, June 2025

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Grosvenor has announced works have started on its multi-million-pound transformation of Grosvenor Square in London’s Mayfair, heralding the creation of an extraordinary urban garden with groundbreaking environmental credentials. The largest private investment in public green space in the West End for a generation, the rejuvenated Grosvenor Square will be a radical reimagining of London’s largest garden square, demonstrating how green spaces in cities can work harder for nature, and the wellbeing of those who rely on them. 

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The fourth redesign of the square in its 300-year history, originated by London-based architecture practice Tonkin Liu and delivered by leading design practice BDP, pays homage to the original 1720s design, reinstating an oval shaped lawn, framed by a new footpath and a surrounding woodland garden. 

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Featuring c.70,000 new plants, 44 new trees, new wetlands and c. 80,000 new bulbs, the square will be a natural haven for wildlife and habitats, blending beauty and biodiversity to create a place for visitors and residents to reconnect with nature. In total, the redesigns will increase planting across the square from 140 square metres to 8,000 square metres.  Planting at Grosvenor Square is being led by renowned horticulturalist Professor Nigel Dunnett, known for some of the country’s leading urban green projects, including the Tower of London Superbloom and the Queen Elizabeth Olympic Park, alongside leading ecologist Gary Grant.

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Driven by a belief that better engagement makes better places, plans for Grosvenor Square have been developed alongside the community since 2017. Over 7,000 people have fed into the designs, with a particular focus made to encourage young people to share their views, ensuring the proposals reflect the needs, aspirations and values of residents, businesses and visitors.  

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The redevelopment includes a new education building, where programmes funded by The Westminster Foundation will offer opportunities for children and adults to learn about biodiversity, the environment, climate change and the square’s rich history. Providing further community benefits, a new kiosk serving refreshments, public toilets and 300 additional places to sit and relax will be provided.  Grosvenor Square will contribute to Grosvenor’s commitment to increase the biodiversity of the green spaces it manages across London, supporting urban climate resilience, helping to regulate urban heat island effects and mitigate flood risk. As part of this, extensive decompaction works are being carried out at the square, enabling it to absorb over 1.4 million litres of stormwater. 

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Part of a multi-year strategic investment to ensure Mayfair remains a pre-eminent location to work, shop, and live, Grosvenor Square will complement Grosvenor’s nearby South Molton project, the West End’s largest mixed-use scheme, set to create a vibrant mix of new offices, retail, cafes restaurants and homes.  

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The Duke of Westminster said: 

“Our ambition is for Grosvenor Square to once again become a treasured green space for everyone to enjoy and where people of all ages can reconnect with nature in the heart of the city. Building on its long history, this revitalisation will breathe new life into the square for current and future generations. From increasing biodiversity to creating new opportunities for learning and education, the transformation has been shaped by the thousands who shared their ideas and voted on the design. We’re deeply grateful for the community’s support.”

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James Raynor, CEO, Grosvenor Property UK said: 

“Grosvenor Square will be one of the world’s most outstanding and innovative urban green spaces, responding to the climate emergency whilst inspiring joy, delight and wonder.”

“This voluntary investment for the benefit of the public epitomises our unique role as custodians and long-term stewards of Mayfair. It is testament to our commitment to placemaking, environmental leadership and community engagement, and will ensure Mayfair remains a pre-eminent place to visit, live and work.”

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Mayor of London, Sadiq Khan, said:

“As the world’s first National Park City, it’s great that a new green haven is being created in Grosvenor Square in the centre of London where wildlife will be able to thrive.  “This private investment is fully aligned with our ambitious London Growth Plan and will lead to a transformation that will blend beauty and biodiversity to create a place for visitors and residents to reconnect with nature.  “I look forward to seeing the transformation of Grosvenor Square into another of London’s world-leading urban green spaces as we continue building a greener, more prosperous London for all.”

 

Nigel Dunnett, Professor of Planting Design and Urban Horticulture, University of Sheffield said:

“We are looking to set a new standard for biodiverse public spaces in the capital, bringing the exuberance of a rich natural environment into a London square in a way that hasn't been done before. Through an innovative and ambitious approach to planting, we are championing sustainability and climate-adaptation, swapping low diversity amenity grassland for sparkling flowering lawns, and creating extensive areas of new woodland plantings beneath the existing London Plane trees, to create new wildlife havens and gardens that will look fantastic year-round.”

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Alex Clarke OBE, September 11 family member said: 

“For many years, the Memorial Garden in Grosvenor Square has been a highly valued place of peace and remembrance for the families of the 67 British victims of the September 11 attacks.  As a family member, a passionate amateur gardener and former Grosvenor Square volunteer, I’m thrilled that the square is set to become a place of natural tranquillity. Its rich landscape and birdsong will enhance the memorial’s setting and offer a calming retreat from the hubbub of daily life.”  

 

Works are expected to complete in Summer 2026.