The Sunday Times will publish its annual list of the countries wealthiest people this Sunday, which will show that the Barclay brothers' fortune has shot up from £1bn in 2009 to £1.8bn in 2010, pulling them further ahead of rival national newspaper owners including Richard Desmond and Lord Rothemere.
Ian Coxon, editor of The Sunday Times Rich List, said the Barclay Brothers' upsurge was due "to general wealth increase".
The super-rich brothers, who live in a mock-Gothic castle on their own island, boosted their property, newspaper and retail empire, which includes Littlewoods, in 2009 with the purchase of Woolworth's after it fell into administration.
Richard Desmond, the charismatic owner of the Daily Express and Daily Star, was the second ranked media person, at number 57, with an estimated fortune of £950m. His value has remained unchanged from last year, but he has dropped down from 44 on last year's list.
Viscount Cowdray (68), who chairs Pearson, the publisher of the Financial Times, and Viscount Rothemere, the chair of the Daily Mail & General Trust (DMGT), were the only other two media moguls to make the top 100 of the list.
Media magnates further down the ladder include Felix Dennis, the reclusive owner of Dennis Publishing. Dennis fell from 88 to 132 on the list, though his wealth remained the same year-on-year at £500m.
Public relations guru Matthew Freud and his wife Elisabeth Murdoch, the daughter of Rupert, are ranked 336 on the list, up from 378, valued at £190m.
Adland is represented by Sir Martin Sorrell, the boss of WPP, and advertising gurus Lord Saatchi and Charles Saatchi, whose wealth was valued at £125m apiece.