If Mr Mellor believed his peccadilloes and personal friendships were not a resigning matter, he reckoned without a new licence in the tabloid press to report politicians' affairs - in every sense.
Reports of the free gifts may have finally finished the minister's career, but it was the lurid reports of the de Sancha affair that sparked the investigations into Mr Mellor's private business.
A few decades ago a minister's sex life might have been the subject of speculation, but rarely reported. Today the highest in the land are fair game.
'The lesson I draw from this story is that the level of hypocrisy mobilised among the populace has risen,' Bernard Williams, Professor of Moral Philosophy at Oxford, and former husband of Shirley Williams, the former Labour minister and founder of the Social Democrats, said.
'Tabloid editors have realised that politicians' personal habits sell newspapers. This was not always the case. But if we are going to start taking an interest in politicians' sexual habits, are we to expect politicians to resign all the time as a result?
'I hope not. If we did that, there would be no good politicians left. We would be stuck with the ones with no private sexual vices, the moralisers, the alcoholics and the eunuchs. What kind of Cabinet would that be?'
David Mellor's resignation set a new benchmark in political scandal. He was the first minister to try to hang on to office for so long in the teeth of public exposure of a lurid extra-marital fling.
Recent decades have produced a crop of well-publicised scandals from John Profumo, Secretary of State for War, who resigned in 1963 over his affair with Christine Keeler, through to
Cecil Parkinson, now Lord Parkinson of Cairnforth, who resigned in 1983 as Trade and Industry Secretary when it became known that Sara Keays, his secretary, was pregnant by him.
A century ago affairs were the talk of society drawing rooms but rarely became public, except in the most celebrated cases and then only because of divorce.
Charles Stuart Parnell, the leader of the Irish home rule party, was forced to resign and end a promising political career in 1890 over an affair with another man's wife.
The career of Sir Charles Dilke, a Liberal Cabinet minister seen as a potential prime minister, was also ended in 1885 by an affair with the wife of a Scottish lawyer.
At the turn of the century David Lloyd George was legendary for his womanising. Gladstone, apparently the most upright of politicians, is regarded as deeply suspect by historians for picking up prostitutes in the street.
'Things have certainly changed,' Sir Geoffrey Warnock, Professor of History at Cambridge, said. 'In the past, politicians' private lives were well known to be disreputable. But it was never mentioned in polite society.
'A scandal did not constitute a political disqualification. Everybody agreed not to make a fuss. Now things are very different because newspapers no longer suppress what goes on. People are still getting up to much the same things in their private lives. The public consequences are rather different.'