IN JANUARY Peter Brooke, then Secretary of State for Northern Ireland, provoked unionist anger by singing 'Oh My Darling Clementine' on Irish television on the day of a terrorist bombing. Mr Brooke speedily tendered his resignation to the Prime Minister, who rapidly rejected it.
'It was,' recalled Mr Brooke, who stood down at the general election, 'a perfectly straightforward decision'. He added: 'I was just of the view that I should offer to go. I thought the authority of the Secretary of State for Northern Ireland might be undermined and that was bad for Northern Ireland'.
With a fine sense of timing Mr Brooke was speaking as news of David Mellor's resignation percolated through the House of Commons. In fact it was this newspaper which broke to Mr Brooke the news of the departure from the Cabinet of the man whose job he now has. As someone once said, it's a funny old world.
Last week was something of a classic for the observer of Whitehall resignations. If Antonia de Sancha is to be believed, the events of last Thursday, when Mr Mellor went, had the mark of natural justice. 'You take certain decisions in your life. Whatever the consequences are, you have to deal with them,' Ms de Sancha said.
But later on Thursday an altogether more puzzling event took place. Norman Lamont, the Chancellor, went to the Commons to explain why he had been forced into the biggest economic U-turn in recent memory, and was cheered by his colleagues. Mr Mellor, the Chelsea FC fanatic, must have been as sick as a parrot.
Nearly two centuries since Pitt the Younger quit as Prime Minister in an early example of the ministerial resignation, the ground rules on who goes and who stays remain fuzzy. Many have failed to live up to Mr Brooke's honourable sang-froid, finding resignation the most traumatic episode of their political lives. Just before Anthony Eden resigned in January 1957 after the Suez crisis , the Prime Minister, according to one journalist, 'broke down in Cabinet and cried: 'You are all deserting me.' '
In an interview with the Sunday Times, Cecil Parkinson described the public exposure of his affair with the pregnant Sarah Keays in 1983 as 'like being in a car crash, you can't move, just utterly stunned'.
Had the problems caused by Mr Mellor's affair not been aggravated by other difficulties, he might have set a valuable precedent by surviving revelations of adultery. It was in 1885 that the first bout of similar ministerial travails occurred, when Sir Charles Dilkes was cited in divorce proceedings, the court case giving the 19th-century press a rare opportunity to report a scandal. Mr Mellor's activities look tame in comparison with what readers of the Sun will recognise as a straightforward, 19th-century three-in-a-bed romp. Sir Charles, who was caught in bed not only with Mrs Crawford (the subject of the divorce) but also with her maid, resigned immediately.
Since then all manner of covert debauchery may have taken place in and around Westminster, but no minister has survived a sex scandal. In 1963 John Profumo, Minister for War, left the Government after his affair with Christine Keeler, having compounding his sins by lying to the House of Commons.
Call girls finished the career of Lord Lambton, Defence Under-Secretary of State (Royal Air Force), who resigned and was summonsed for possession of cannabis and amphetamines in 1973.
After another bout of press rumours Earl Jellicoe, First Sea Lord, stunned the political world by resigning abruptly, owning up to 'casual affairs' with call girls.
Sex scandals have, however, caused only a minority of Cabinet resignations. Most ministers who have quit have done so on a point of principle or because they fell out of sympathy with the government line.
William Pitt the Younger was one of the first to go on a matter of principle, in 1801, in protest at the Crown's opposition to a degree of Catholic emancipation in Ireland.
During the 19th century the important principle of Cabinet solidarity, which was to force many departures, was becoming established. This was perhaps best defined by Lord Melbourne, who is reputed to have sat absent-mindedly through interminable Cabinet meetings on the Corn Laws. After agreement was clinched the ministers left, only to hear the Prime Minister call to them, 'Stop a bit. What did we decide? Is it to lower the price of bread or isn't it? It doesn't matter which, but we must all say the same thing.'
Inability to toe the Cabinet line, or clashes with the Prime Minister, have signalled the end of many ministers, including the Chancellor of the Exchequer, Peter Thorneycroft, and his Treasury team in late 1958 over public spending; Michael Heseltine in 1986 over Westland; Nigel Lawson and then Sir Geoffrey Howe during the later years of Margaret Thatcher's premiership. All these ministers felt their position was untenable.
A more difficult category is that of politicians who have resigned because of mistakes or a failure of policy. Previous Chancellors have set a precedent which makes it difficult to foresee Mr Lamont's long-term survival in his current post. Hugh Dalton resigned in 1947 because elements of his Budget were inadvertently leaked several minutes early to a lobby correspondent, but James Callaghan's experience of the humiliating 1967 devaluation is more relevant to Mr Lamont's position. Lord Callaghan and the then Home Secretary, Roy Jenkins, swapped portfolios.
The mood that preceded the resignation of Lord Carrington, Foreign Secretary when the Falklands were invaded in 1982, was recalled in his memoirs, Reflect on Things Past: 'The nation feels that there has been a disgrace. Someone must have been to blame. The disgrace must be purged. The person to purge it should be the minister in charge. That was me.'
The memoirs go on to list another, equally revealing, reason for his departure: 'I had attended a fairly disagreeable meeting of the 1922 Committee (of backbench Tory MPs) and although nobody shouted for my resignation I knew that within the Conservative Party itself my remaining in office was not going to help the Prime Minister'.
Naturally, different ministers react in different ways when the question of resignation comes up: some are more willing to do the honourable thing, others seem markedly more determined to hang on to office.
Over recent decades ministers have generally been less inclined to accept personal responsibility for departmental failings, but there have been individual exceptions. Sir Thomas Dugdale, for example, quit in 1954 over his department's failure to return requisitioned land to its pre-war owner, but five years later Alan Lennox-Boyd did not resign over deaths in a Kenyan prison camp.
The crucial factor determining whether a minister is able to stay in office is the attitude of the backbenchers. Thus the increasingly Euro-sceptical Mr Lamont, cheered by backbenchers uneasy about Maastricht, is safe for the time being. Mr Mellor, never the most popular man about the Commons tea rooms, was wise to quit before the 1922 Committee executive discussed his case.
One minister believes that Mr Mellor's fate was sealed when politicians returned from their holidays to find the 'Mellordrama' raging over allegations of freebie holidays. He said: 'Most MPs, who had been on an expensive holiday paid for out of their own taxed income, were less than sympathetic when they saw Mellor had taken a pounds 20,000 holiday handout.
'The truth is, you can get away with the most tremendous balls-up in government, as long as you don't lie to the House or appear to bring MPs into disrepute.'
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies