Gordon Brown has written to the Metropolitan Police offering his support for the "fullest possible investigation" into the secret Labour donations affair. As the police begin their inquiry into businessman David Abrahams' payments via third parties, the Prime Minister has given his backing to his deputy Harriet Harman. She has revealed it was Mr Brown's leadership campaign manager who suggested she seek a donation from an associate of Mr Abrahams, but has denied implicating the Prime Minister.