The Last Diaries, by Alan Clark <br></br>Diaries 1987-1992, by Edwina Currie <br></br>Free at Last: Diaries 1997-2001, by Tony Benn

We all know about the scandals. But D J Taylor is truly shocked by the ignorance and naivety of political diarists

One of the sharpest accounts of the psychology of the average diary-keeper comes in Patrick Hamilton's novel Mr Stimpson and Mr Gorse (1953). Here, considering the windy effusions of a certain Mrs Joan Plumleigh-Bruce, Hamilton notes that she, "like most diary-writers of her kind, although seemingly making a detached statement, was in fact doing something else as well. She was writing a letter to an imaginary woman friend – a friend who was, occasionally, so disagreeable as to be almost an enemy – and with whom, therefore, it was necessary to hold one's own."

Every diary has a theoretical audience beyond its compiler, but even taking into account the exceptional conceit of Mrs Plumleigh-Bruce, this seems rather harsh. Looking at some prime published specimens of the past decade, whether written by ailing political fixers or veteran literary men, one detects more complex motives.

Woodrow Wyatt (three volumes, 1997-99) began on his half-million-word opus with the deliberate aim of providing money for his heirs. Anthony Powell (three volumes, 1995-97) set out to subdue a creative impulse that could no longer find expression in fiction. Doubtless vanity accompanied them on these pleasant cruises through the drawing rooms of the great, but it was not vanity that encouraged them to set sail. Or not quite.

To inspect this autumn's crop of political diaries – Edwina Currie's ominously slim account of late-Eighties ministerial cut-and-thrust, Alan Clark's sober diminuendo, the 700 pages (edited and selected at that) of Tony Benn's last 10 years – is to be struck immediately by the varying perspectives. Clark and Benn are clearly writing for posterity, but in each case a different kind of posterity. To Clark, perhaps, this posthumous arbiter is not much more than Mr Worldly Wiseman sitting post-prandially in his club – a kind of spiritual version of the chairman of the 1922 Committee – silently concluding that the diarist, though occasionally a high-grade shit, was patently One of Us.

For Benn, you suspect, the project has a grander focus. That posterity is not so much the Executive of the Campaign Group as some Socialist historian of the future – possibly even the historian of a society which has miraculously reforged itself on Bennite lines – tapping his pencil against the page to murmur, "How right that man was."

Set against these devious strategists, Mrs Currie's goals – cheering herself up, justifying her decisions – look horribly prosaic, although she does manage to locate one of the form's great motivating forces.

Why is she doing this, she wonders at one point. "Because I need someone to talk to; because I have a ringside seat and I'd eventually like to share my view of events, if only with myself when I'm a self-indulgent 90-year-old." For Clark and Benn, the goadings of the historical process; for Currie, simple loneliness.

All three, however, share that fundamental diarist's need to be noticed, recognised and appreciated. The nods of passers-by infallibly console them. Compliments that a child of five might think forced are gratefully received and written down. Tony Benn has a particular ear for obliging train drivers ("I wouldn't do this for John Major") and respectful taxi-men ("My dad is 85 and such an admirer of yours"). Even a negative reaction is better than nothing, or so we infer from the young woman who walked past Clark on election day 1997 muttering, "I hope you lose – philanderer."

With Benn, this perpetual preening is conducted so artlessly that it becomes a point in his favour. There is an innocuousness about his delight in being offered a lift in the PM's private jet after John Smith's funeral, or his recitation of the MPs who signed the early-day motion congratulating him on his half-century in the House, that more self-conscious compilers could never get away with.

There are other similarities. Reading accounts of past political times by those in the know, one looks for prescience. It is rather shocking, consequently, to discover how inaccurate, misinformed, misguided, over-optimistic or just plain deluded everybody is. "It looks like we're heading for an ignominious defeat in the election," Currie declares on 6 April 1992 (the Conservatives defied the pollsters). "I have a sort of feeling he might do well," Benn decides, after the Tatton Conservatives have renominated Neil Hamilton (he goes down by 11,000 votes). "We're going to win," Nicholas Soames reassures Clark in spring 1997 (the Labour majority extends to 165 seats).

If establishing why a diary gets written is difficult enough, working out whether it succeeds is harder still. Political diaries have the additional drawback of being caught up in procedural detail, and starring minor figures of the moment (I had practically forgotten John Moore, Currie's boss 1987-89 and hotly tipped as a future Tory leader). Of the current trio, Currie's is simultaneously humdrum and coy, though interesting on the minor government background; Clark's stylistically quirky ("quite ordinary words" turning up in "speech marks") and a mournful amalgam of personal and political decay. Free at Last, on the other hand, offers perhaps the funniest instalment yet in the career of that great English comic character: Tony Benn.

It is usual to describe diaries of this sort, with their unconscious humour and stupendous lack of guile, as "Pooteresque". In fact, Benn has none of Mr Pooter's affronted dignity. The temptation is to write off the entire exercise – the not knowing who people are ("somebody called Derry Irvine"), the laborious glosses (the New Musical Express marked down as "the very popular rock-and-pop magazine for young people") – as a colossal pose. Yet all the evidence suggests that Benn's naivety is perfectly genuine, that he really does think Ali G is being serious and fails to recognise Sebastian Coe.

There is something rather wonderful, too, about a former Cabinet minister being prepared to reveal that he and his wife's pet-names for one another (this chunk covers Caroline Benn's death with unselfconscious poignance) were "Greensleeves" and "Pixie". He is courteous to political enemies (Norman Tebbit and Ian Paisley get startlingly good marks), and his political stance approximates to that of some ancient Old Believer contemplating the remnant of the Jacobite army after Culloden.

There is a peculiarly rapt, child-like quality to Benn's ruminations. I had an odd, final vision of what he might have been like in Downing Street, had he ever got there: attacking the despatch boxes with infant wonder, leaving havoc in his wake.

D J Taylor's biography of George Orwell will be published next year