Alan Watkins: By the standards of Fleet Street, his intake seemed to me to be on the moderate side

Mr Charles Kennedy tried to pull a fast one and almost succeeded. He was defeated by his parliamentary colleagues. The political effect of his resignation is that it makes the contest open to Sir Menzies Campbell and Mr Mark Oaten. They had said that they would not stand against Mr Kennedy if he had followed his original proposed course and been a candidate himself.

Sir John Major succeeded by following a similar course in 1995, even if on that occasion the circumstances were rather different. He resigned as party leader but not as Prime Minister. There is another Conservative parallel to this path, provided by Margaret Thatcher in autumn 1990. Owing to a natural tendency to conflate, there is a disposition to depict this crisis as having been over in days. On the contrary: it lasted for weeks before it was finally resolved.

At the beginning, Mrs Thatcher was bombastic, vainglorious, utterly preposterous. She was joined by acolytes such as Sir Bernard Ingham and Lord Baker, with their calls to put up or shut up. And she ended in tears.

Sir John's experience was happier. Even so, there was a question about whether he was behaving in a constitutionally proper manner. For how could he properly remain Prime Minister when there were doubts, raised by himself and nobody else, about whether he commanded the support of his parliamentary colleagues? Oddly enough, this matter was brought up only by Enoch Powell and by myself. No one paid the slightest attention.

Sir John failed to secure the support of roughly a third of his colleagues, but Lord Salisbury (then Lord Cranborne, the Leader of the Lords) organised posses of peers and of MPs to ride to the microphones to spread the news that the Prime Minister had received a clear triumph. Everyone believed them and the whole operation was pronounced an unqualified success.

Even on Friday, it was difficult to see how Mr Kennedy's original exercise could turn out in the same way. Already politicians and observers of the passing scene were alike playing the traditional English game of Hunt-the-Issue. This goes as follows: the issue (sometimes varied to "the real issue") is not whether Bloggs went to bed with Debbie/took drugs/went into the Priory (delete as applicable). It is whether he lied about it.

Mostly sex has triumphed easily over drink, drugs or treatment for either addiction. We are more interested in entangled bodies than we are in strange substances; still less in simple intoxication. But recently there have been signs that drink and drugs have been coming up fast on the rails, always allied, of course, to some allegation of a want of frankness or, sometimes, of straight mendacity.

My own conviction is that civilised life is possible only if certain questions not only cannot be asked but should not be answered, truthfully or otherwise. It is not the case that everyone has the right to know everything about everybody else. Mr David Cameron made a promising beginning along these lines, though he confined his own law of privacy to one's early life. This remained conveniently undefined; whereas I should have thought that one's later life remained equally significant, if not more so.

Mr Kennedy seems to have gone in for denial on a heroic scale. He should have told Mr Jeremy Paxman, Mr Jonathan Dimbleby and other licensed inquisitors to mind their own business. Not only did he not do this: he went into considerable detail to controvert the charge of excessive drinking. He went further still: for he and his party took legal action against The Times newspaper after one of its columnists had provided chapter and verse for one of his alcoholic delinquencies.

He succeeded, though I remember thinking at the time that the retraction, when it appeared, was not much of a retraction: to an apology it was no apology. Far be it from me to safeguard the interests of Mr Rupert Murdoch. He is well able to attend to them himself; none more so. But if The Times was out of pocket over the action taken by the Liberal Democrats in defence of Mr Kennedy, it seems to me that it is fully entitled to ask for its money back from party funds.

By the standards of consumption of the great men of Old Fleet Street among whom I was lucky enough to grow up - Henry Fairlie, Philip Hope-Wallace, Derek Marks, John Raymond, Maurice Richardson - Mr Kennedy's intake always struck me as being on the moderate side.

Nor should we forget Malcolm Muggeridge. Something over 50 years ago, he was not only deputy editor of The Daily Telegraph and then editor of Punch but seriously considered for the editorship of both the Daily Mail and The Sunday Times. Today he would be excluded from consideration for such exalted posts, not so much because of his promiscuous heterosexuality - which might, indeed, be thought to add to his qualifications - as because of his excessive drinking. In later life, as we know, he changed. He once said to the journalist Charles Wheeler: "When you reach 60 you have to decide whether to be a saint or a sod, and I've decided to be a saint."

Wheeler replied: "What sort of progress are you making?"

Mr Kennedy has another 14 years to go before he is 60 but has already decided to relinquish strong drink. We live in a more puritan, a less tolerant and, in its way, a more authoritarian society than that of the younger or, for that matter, the older Muggeridge. Drink is more disapproved of: but, at the same time, confession of error - as with Cherie, Mrs Blair, and the Bristol flats - public repentance and promises of reform are looked upon as the highest personal and, indeed, social goods, however implausible they may be. Even in this new air, I did not think Mr Kennedy was going to get away with it.

Eight years ago I published a book on how people became Prime Minister. In the Introduction I wrote: "There may be trouble in store all round." This was a reference to the growth of mass-party democracy, or some variant of it, and to the possibility that the MPs and the party in the country might find themselves at odds about the leader.

So far, the luck of all three parties has held up remarkably well, with only the short-lived Mr Iain Duncan Smith as someone imposed on his parliamentary party, and the most recent elected candidate, Mr Cameron (the indirect cause of much of Mr Kennedy's trouble), another example of happy unity. The Liberal Democrats must hope that they do not end up with another Duncan Smith on their hands.