Celebrity chef Jamie Oliver, at 29, is the youngest person on the list

But even with �20m in the bank, they lag behind others who have completed vocational courses such as hairdresser John Frieda, 53, who is worth �170m.

The list, compiled for the City and Guilds training body, is headed by Phones 4u magnate John Caudwell.

The 52-year-old is worth an estimated �1,280m - up from �840m last year.

Jamie Oliver, 29, who took a City & Guilds NVQ in Home Economics, is the youngest on the list and doubled his financial value from �10m last year.

It has secured him a place in the top 25, ahead of household names comedian Billy Connolly, with �12m, gardener Alan Titchmarsh, with �10m, and fellow chef Gary Rhodes, with �6m.

Fashion designer Karen Millen, 43, also features in the rich list at joint 18 with Jamie Oliver, Gordon Ramsay, 38, retail magnate Michael Clare, 49, and fashion guru Alexander McQueen, 35.

City & Guilds top six 2004 John Caudwell, 52, Mobile Phones �1280m Trevor Hemmings, 69, Gaming & Leisure �700m Laurence Graff, 66, Diamonds �450m Jim McColl, 53, Industry �330m John Frieda, 53, Hair care �170m Sir Stan Clarke, 71, Property & Racecourses �148m

The list, put together by Philip Beresford, author of the Sunday Times Rich List, reveals the collective value of the nation's top 25 "craft millionaires" has risen �1.5bn in 12 months - from �2.7bn in 2003 to �4.2bn in 2004.

Chris Humphries, director general at City & Guilds, said the list "belies the myth that obtaining a vocational or apprenticeship qualification provides a career cul-de-sac".

"It's the qualifications and training that all of the individuals on this and last year's list received that equipped them with the skills they needed to become the millionaires they are today," he said.

"All too often vocation courses are considered second rate."