Lydiate has been one of the stand-out performers for the Dragons this season and is one of just two Rodney Parade players - alongside lock Luke Charteris - called up for Wales coach Warren Gatland's 29-man autumn Test squad.

BBC: Lydiate dreaming of Wales debut

His move to England, which is expected to take effect after the 2011 World Cup in New Zealand during the autumn, will further test Wales coach Warren Gatland's desire to have his players based in Wales.

BBC: Wales prop Craig Mitchell to join Ospreys' exodus

He won his third cap at 12 in June's second Test against South Africa, impressing Wales coach Warren Gatland who wants to see more of Roberts there.

BBC: Blues to move Roberts to centre