A community garden celebrated its 20th birthday with a party and the unveiling of a new eco-classroom on its allotment site.

Moulsecoomb Forest Garden and Wildlife Project opened its gates to the public with the offer of food, drinks, bush-craft, party hats and a treasure hunt.

Project manager Warren Carter, 48, said 20 years ago he and his friends just wanted to get an allotment, never dreaming it would become the all-inclusive community project it is today.

He said: “Over the years it just keeps evolving. The more you do things and the longer you run, people come to you. A lot of it is being open to ideas.”

Now the garden off Crespin Way, Moulsecoomb, spans nine allotment sites and an area of woodland that was added to the South Downs National Park due to the campaigning of Warren and his team.

The main aim of the project is to bring people together and support those who may otherwise be facing challenges in society.

Primarily, children experiencing educational or behavioural difficulties at school are encouraged to help out and learn about gardening, cooking, and forestry among other things.

Amyas Gilbert, 28, an outdoor youth worker, said the garden should be as therapeutic as it is educational.

He said: “I think the biggest impact on the kids is confidence building. Up here they feel like trusted, valued members of society.”

The new two-storey eco-classroom has a frame made of sweet chestnut, floorboards of douglas fir and walls made of straw bales with lime rendering.

Carpenter, Russel Kingston, 26, said: “Building it was tiring but rewarding, definitely. I think it will attract a lot of people to the garden because of its eco credentials.”

Guests of all ages enjoyed the birthday party, exploring the gardens, drinking tea and eating pasta with home grown pesto or burgers cooked in a clay oven.

Visitor Graham Lee, a 63-year-old psychotherapist from Brighton, said: “I think it's fantastic. It's like an outside classroom – plus it puts kids in touch with nature and sustainability.”