Princess Anne toured the 34-acre site and met some of the youngsters who benefited from it. She also unveiled a special commemorative plaque.

The ABLE project in Wakefield is run by the ABLE Partnership Ltd and combines a unique fish farm and horticultural operation.

Groups and individuals attend daily to work on the various elements of the project which include a large scale fish farming operation, a community orchard, a huge vegetable patch and a range of construction and joinery tasks.

It operates an alternative education provision, working in partnership with the Green Business Network, Yorkshire Water, Wakefield District Primary Care Trust, West Yorkshire Probation Service and the Wakefield District Community School.

Graham Wiles, project manager, said: "The project is an alternative education scheme and we take young people who have been excluded from school and offenders doing their community punishment.

"It's a very big environmental scheme. We have this whole virtual circle of re-use of resources.

"All of the work is being done by young people as part of an education programme."

Speaking about the royal visit, Mr Wiles added: "The visit was terrific. Princess Anne has a lovely personality and warms the hearts of everyone that she speaks to.

"It's good for Wakefield, it's good for the kids and it's good for the project."