The United Kingdom is one of the countries taking part in GREEN×EXPO 2027. The Yokohama expo is also known as the International Horticultural Expo. On 30 July 2026, the UK and the GREEN×EXPO Association (formally the 2027 International Horticultural Expo Association, a public interest incorporated association) signed their official participation contract. The sources we reviewed do not give a date for when the UK first announced its intent to take part. The full list of participating countries is on our countries guide.
The basics
Everything in this table comes from the Ministry of Foreign Affairs of Japan’s country data, in the version dated 8 December 2025.
| Item | Detail |
|---|---|
| Official name | United Kingdom of Great Britain and Northern Ireland |
| Area | 243,000 square kilometres (about two-thirds the size of Japan) |
| Population | 68.27 million (UK Office for National Statistics, 2023 estimate) |
| Capital | London (population approx. 9.09 million, UK Office for National Statistics, 2024 estimate) |
| Language | English (with Welsh, Gaelic and others used in some areas) |
| Religion | Church of England and others |
| System of government | Constitutional monarchy |
| Head of state | King Charles III (acceded 8 September 2022) |
The same source gives these figures on the Japan–UK relationship.
| Item | Detail |
|---|---|
| Japanese nationals resident in the UK | 64,066 (October 2024) |
| UK nationals resident in Japan | 21,139 (December 2024) |
| UK visitors to Japan | 437,200 (2024) |
| Japanese visitors to the UK | 225,000 (2023) |
Official exhibit information
The signing ceremony for GREEN×EXPO 2027’s official participation contract with the United Kingdom took place on Thursday 30 July 2026 at the British Embassy Tokyo. According to the announcement, Ambassador Julia Longbottom attended, alongside Jun Niimi (Government Commissioner-General for the 2027 International Horticultural Expo), Catherine Wilde (UK Government Commissioner), Masato Kawamura (Secretary General of the GREEN×EXPO Association), Manabu Nagai (Parliamentary Vice-Minister of Land, Infrastructure, Transport and Tourism) and Norikazu Suzuki (Minister of Agriculture, Forestry and Fisheries).
According to the Association, the UK will use its participation to present expertise in horticulture and landscape design built up over many years, along with innovation in sustainable technology. A British garden, described as one where tradition and beauty live on, is planned for the venue. The stated aim is for visitors to experience British garden culture surrounded by flowers and greenery, and to think about a sustainable future.
The exhibit’s name, size, opening schedule and designer had not been announced as of September 2026.
A cultural primer: British gardens and the RHS
For background on British garden culture, the history of the Royal Horticultural Society (RHS) is useful. The RHS was founded on 7 March 1804 as the Horticultural Society of London, by just seven people including the botanist Sir Joseph Banks and the horticulturist John Wedgwood. Its stated aim from the outset, according to the RHS, was to advance the science and practice of horticulture through evidence.
Prince Albert became the Society’s president in 1858, and a new royal charter in 1861 gave it its current name, the Royal Horticultural Society. In 2024, King Charles III was named its patron.
The RHS now runs five gardens: Wisley in Surrey (acquired in 1903), Rosemoor, Hyde Hall, Harlow Carr, and Bridgewater, which opened in 2021. According to the RHS, Wisley’s visitor numbers have grown from about 6,000 in its first year to more than a million today.
The RHS also runs the Chelsea Flower Show, held every year since 1913, as well as the Hampton Court Palace Garden Festival, the Tatton Park Flower Show and the Malvern Spring Festival. Membership opened to the public in 1978 for an annual fee of £7.50, and the RHS says it is now developing tools such as the RHS Grow app and an AI-assisted advice tool called ChatBotanist to make gardening more accessible.
We also checked the official sites of VisitBritain and the British Embassy Tokyo, but found nothing specific there about garden or horticultural culture.
Our take
The RHS’s history suggests British garden culture has kept renewing itself while holding on to tradition. The growth in Wisley’s visitor numbers and a Chelsea Flower Show that has run for more than a century are consistent with that. The GREEN×EXPO 2027 announcement describes the UK’s garden in terms of tradition and beauty, and we think that matches the RHS’s history. What the Yokohama exhibit will actually look like has not been announced yet, so we will come back to it once the details are out.