When asked recently about where ministerial buck-passing stops, Sir Robin Butler, the Cabinet Secretary, said that ministers were accountable but not responsible.

Few would argue that the behaviour of some ministers is responsible - step forward philanderers David Mellor, Tim Yeo and Stephen Norris - but there is a growing feeling that members of the Cabinet are less and less likely to be accountable for their departments failings.

Michael Howard's leech-like grip on his job has come to symbolise the unwillingness of ministers to go when serious mistakes are made in contrast with the regularity with which members of the Government fall after being caught, literally, with their trousers down.

When Norman Lamont, the former Chancellor, refused to withdraw the pound from the ERM, costing the taxpayer billions at the hands of foreign speculators, he did not resign. Yet when Tim Yeo, a former Minister of State at the Department of Environment, w a s found to have adulterously fathered a child, he was out.

When Michael Heseltine, President of the Board of Trade, Kenneth Clarke, Chancellor, and Malcolm Rifkind, Defence Secretary, were found to have signed gagging orders that would have seen innocent men jailed over the Matrix Churchill scandal, they did no t resign, arguing they were only following orders (from the Attorney-General, Sir Nicholas Lyell).

Contrast such standards with 1982 when Lord Carrington, the then Foreign Secretary, resigned over the Argentine invasion of the Falklands even though he had not been responsible for missing the signs of an Argentine military build up.

Or compare the same standards with the decision of Tam Galbraith, the former Admiralty minister, to resign during the 1962 Cuban missile crisis because his name had been linked with Vassall spy case. He went because he feared the rumours would damage theGovernment.

"I would only envisage a minister resigning these days if he was involved in some serious mistake in international high politics - if, for example, he rejected advice to pull British troops out of Bosnia and they were killed," said Professor Patrick Dunleavy, professor of government at the London School of Economics. "Britain is so unimportant on the world stage these days that ministers are reduced to interfering in petty domestic matters and tinkering with matters about which they know nothing.''

The excuse trotted out by Michael Howard for his refusal to resign over repeated prison gaffes is that he is responsible for matters of policy, not for day to day operations.

And he is not alone in adopting the policy-versus-operation argument; it was used by the then Labour Home Secretary, Roy Jenkins, when the Soviet spy George Blake escaped from Wormwood Scrubs in 1966. And it was used again by Kenneth Baker when the IRA suspects Nessan Quinlivan and Pearse McAuley broke out of Brixton jail in 1991.

But Dr Geoffrey Marshall, Provost of Queens College, Oxford, baulks at the idea that ministers were more honourable in the past. "The idea that ministers should take responsibility for all the actions of their civil servants is one that has never really been adopted,'' he said. "Whenever anything went wrong, ministers would always try to get away with it."