Great Men don't write great diaries

Spare me sobriety and historical accuracy: what I want from a published journal is passion, perversion, bias and shameless bad behaviour.

SH1T hot ... Alan Clark. Photograph: Jane Bown

Diaries, or rather great diaries, are not chronicles of their period; they do not show the tantalising inner thoughts of great men. They are biased, corrupt and misleading. Utterly useless to historians, they are literary treasures.

The vast majority of political diaries are like Hitler's: fakes. Field Marshall Haig's diaries have been a key source for military historians and their backlash against the "lions led by donkeys" myth of the First World War. That the diaries were proven to have been reworked years later hasn't stopped them.

Then again, honesty is not always the best policy. The most famous living political diarist, Tony Benn, told the audience at this year's Hay festival that "if you write down what has happened every day to the best of your recollection... then other people can decide." He has written 12m words saying what he has done every day. Very few of those words discuss hangovers, naps in cabinet meetings or dreams of undressing young researchers. He's above all that.

He has, he told the Guardian in one of this year's Haycasts, an absolute principle of never removing a mistake he has made. While this may well be true of the great political issues of the day where he took a position he now regrets, Benn is never willing to portray himself as a fool in the way Pepys, Boswell, or even Alan Clark do. Because of this, I find him a bore. The king of the unashamed chroniclers, on the other hand, was (and is) Kenneth Tynan. It's unlikely that Tony Benn would ever have recorded an honest account of his day that started, as Tynan's did on October 1 1978: "Tested penis by masturbation. Can achieve moderate stiffness in lower part of trunk."

There are other media in which diaries can work. Jeffrey Lewis, a now pretty much iconic underground musician and comic book artist, has serialised his life in drawn diaries. He obviously isn't the first to do so (was that Harvey Pekar?) but Lewis is the one who, for me, ranks with the traditional greats. He has the poignancy and bleak humour to mock his own attempts, as a New York-raised Jew, to become a music legend in Texas. His thoughts on encountering a strange offer of a bed when hitchhiking to Eastern Europe: "If he is a con-man pervert, he's doing such a good job of it that he deserves to rape and kill a traveller once in a while." Sadly, Lewis stopped his diaries when he got his first girlfriend. He was in his late 20s.

The oddest diary I have come across is by a (minor) politician's wife. Labour of Love by Janet Jones, wife of Ivor Richards (once, briefly, Labour leader in the Lords), is astoundingly poorly written and unengaging to an almost masterful degree. Sadly, the copy I got for 10p from the remainder section in WH Smiths has long gone to the charity shop so I am unable to quote from it, but the salient point is that she isn't trying to help her husband's career but attempting to get her own, as an (unpublished) writer of children's books, off the ground. And so we get bedtime chats about Lords reform and comments on how Cherie dresses at receptions muddled together with the dog being sick and another rejection coming in for her picture book.

It's not that a dull life doesn't make for a great diary. Alan Bennett has been whispering his day-to-day observations in Yorkshire prose for the last 30 years. He actually confesses very little about himself - even his sexuality warrants only a brief mention - but he does present us with a quietly eccentric universe which he observes from the outside in pithy one-liners:

20th March, 1983 [with his elderly mother] She wants to say, "What a grand view," but her words are going too."'Oh," she exclaims. "What a big lot of About." There are sheep in the field. "I know what they are," she says, "but I don't know what they are called." Thus Wittgenstein is routed by my mother.

Another playwright, Simon Gray, is for me our most underrated living diarist. Self-knowledge, venom and wit have filled six volumes of diaries over the years; they've seen him go from affluent alcoholic to liver-wrecked, Diet Coke-addicted bankrupt. As a result of this, and of the deaths of his two best friends (Alan Bates and Ian Hamilton) the last two diaries have taken on a sombre but beautiful tone. He still retains a bleak, even apocalyptic, sense of humour.

The best diarists aren't necessarily the best of men, though the best are, as it happens, usually men: grumpy, defeatist, perverted, drunken, misanthropic and misogynistic. Most importantly, they're not afraid to let the reader know this about them. It is unlikely, to say the least, that Alan Clark will be remembered as a better parliamentarian than Benn, but every one of the latter's 12m words will no doubt be forgotten in favour of Clark's fantasy of urinating out of a ministerial office onto the "ant-like minions below". Boswell rapes and bribes his way through the London Journal but I'd rather read him than the censored Alastair Campbell any day.