Gardeners and activists hired by the Royal Horticulture Society to help them reach out to young and disadvantaged people, he said that when he left the role, its flagship Chelsea Flower Fair celebrated the “exclusiveness of equity”.

Tayshan Hayden-Smith, 28, was asked to become a young man and community ambassador for charities in 2022. But now he says after working with RHS for three years, he lost hope that it really hopes it will become easier to get.

Hayden-Smith announced this week that he resigned on Instagram on the eve of RHS's biggest annual event, Hayden-Smith said: "I got into this role with intention and optimism. Reflection, I'm naive now to see me too."

"What I'm going to learn is that there is no reallocated representation - power, resources or decision-making - not justice. Working in institutions that are not ready to listen, adapt or truly share space, is only that far away."

He particularly criticized the Chelsea Flower Show: “Year after year (the event) sets a precedent to celebrate the wonder of sustainability, the exclusivity of equity.”

The Royal Horticultural Society is one of the oldest horticultural societies in the world. It was founded in 1804 and is a forum on horticultural experimental ideas. It runs one of the UK’s National Community Horticultural Programmes, investing millions of pounds across the country and promoting it nationwide.

Its flagship event is the Chelsea Flower Show, held for more than a century on the reasons for Chelsea Royal Hospital, and is one of the world's leading international gardening events.

Hayden-Smith is known as a gardener after the catastrophic fire in Grenfell Tower, which shrouded his home in 2017. When some in his community turned to art or music to express their grief in their 72-year-old life, he began to lean towards the unused green space nearby, which eventually turned into the peaceful Greenfield Gardens.

Encouraged by success, he formed a nonprofit Grow2Know, which empowered young and disadvantaged people through guerrilla gardening and reclaimed unused space in their naturally impoverished internal urban communities.

In 2022, just five years after picking up the trowel for the first time, Hayden-Smith received funding at the Chelsea Flower Show. But even then, he doubted its exclusivity.

"The five-day festival... never felt like it was for me." Soon after, the RHS asked Hayden-Smith to be one of its ambassadors.

Hayden-Smith told the Guardian that there was a specific flash point at this year's Chelsea Flower Show. He said the RHS owner rejected his proposal to open the event to members of the community living nearby, traditionally seen as a big brother.

Hayden-Smith lives and grew up in North Kensington, just minutes from the affluent community of the show, but expects to live a life of 20 years less.

“Hopefully, due to local circumstances, due to differences and inequality within the borough, the Chelsea Flower Show has been around for over 100 years, so it is a unique opportunity to redistribute, create access that can really be bold enough to attract a wider community of people.”

“The reaction to this is that despite it being at the doorstep of the Chelsea Flower Show, we cannot prove to support this particular community.”

A spokesman for RHS said: “RHS supports Grow2Know of the North Kensington Borough project by providing direct funding to community gardens (£30,000).

“We also hosted and funded a fundraising event for the same community garden, asking local RHS members to support the project and participate in community engagement through the planting event.

“RHS offers one of the largest national community gardening programs, investing millions of dollars in school horticulture, community advocacy and grassroots projects across the country.

“We have a major partnership with the NHS to provide community welfare gardens and have partnered with Natural History Museums supported by the Ministry of Education to bring nature to schools in England.

“All the gardens at RHS Chelsea Flower Show will be a community green space in places like hospitals and schools across the UK. The world-renowned event also raises important funds for RHS to engage in community advocacy as part of its national community work program.”

In recent years, in addition to showing cutting-edge garden designs, the show has included an increasing number of gardens focused on inclusion, such as the ADHD Foundation Garden, which celebrates neurodiversity.

It has also been newly excavated into containers and balcony gardens as some people cannot access large tracts of land.

He said in 2022, Jason Williams, known as the Cloud Gardener, designed his balcony cabbage to perform, “like a beacon of hope for people like me who struggle with themselves in their mental health and show them that anything is possible.”

Williams just confirmed that he will be part of the lineup for this year’s show.

But Hayden-Smith said his efforts to get charity to understand the life experiences of people like him were resisted, and sometimes even hostile.

“I felt a lot of different discomfort during my three years as ambassador at RHS,” Hayden-Smith said. “No one wants to bother or nuisance under the guise of trying to do something positive.”

He added: "It feels like a little bit of a need to protect Chelsea's flower exhibition...I feel like it has become very selfish and there is this influence, and there is this influence, and there is this influence, and the Chelsea Flower Exhibition offers this network, and there is not a lot of places to offer."