The Tories accused the Government of operating "double standards" but Peter Mandelson, Minister Without Portfolio, denied this, and defended Mr Cook.
Mr Mandelson said Tony Blair had never tried to preach to ministers about their private lives. "He made it absolutely clear that he had no desire to pry into ministers' personal lives and he said he had no desire to return to the age of Victorian hypocrisy about sex or preaching to people about their private lives."
But last night the Tories returned to the attack. They produced leaflet issued by Labour during the final days of the Uxbridge by-election attacking the Tory party chairman, Lord Parkinson, for the "indescretion" of his affair with his secretary, which led to his sacking from Lady Thatcher's government.
Friends of Mr Cook said the breakdown in his marriage was "another casualty of Westminster". One senior Labour backbencher told The Independent that a number of MPs in the new intake were finding difficulty in the degree of separation from their families, and there could be a move to ease the demands on MPs voting every night.
Mrs Cook knew about her husband's relationship with his secretary, and had been fighting to save the marriage, but Mr Cook told her on Friday, after being confronted by journalists about the affair, that he had decided to leave. He said in a statement: "I want to make it clear that the responsibility for this is entirely mine."
Government sources said there was no comparison with ministerial resignations from the former Tory government. Labour had then accused ministers of hypocrisy because John Major had launched the "back to basics" campaign for family values.
There is a tradition at Westminster of MPs marrying their secretaries. These include Douglas Hurd, and Lord Hailsham. Colin BrownReuse content