Damian McBride compared his activities as Gordon Brown's spin doctor to those of a "rogue trader in the 1980s", saying Labour leaders were unaware of the way he operated.
McBride told ITV's Daybreak: "I'd compare it to when we had some of the rogue bankers ... people weren't asking enough questions about how they were making their profits."
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Labour strongholds tended to remain so - apart from a major loss for the party in Dudley.
Labour suffered a "terrible" defeat in Rhondda but has already won 16 Welsh Assembly seats as it looks to record a fifth term in office.
UKIP have made further gains in the local elections in the Anglia region and the Conservatives have won back control in Peterborough.