There are diaries, and then there are diaries written for publication. Editing those of Sir Noël Coward a decade or so ago, with his lifelong friend Graham Payn, it occurred to us that though they had languished for several years in a bank vault, so sharply and professionally and, sometimes, all too tactfully were they written that Noël had clearly meant us to get them into the bookshops sooner or later.

Sir Alec Guinness’s new volume is similarly sharp and, alas, equally circumspect. Following his only book of memoirs (Blessings in Disguise, 1985, now reissued in a revised edition by Hamish Hamilton, £18), which was a slender, masterly disappearing act ending late in the 1950s, My Name Escapes Me gives us just one year, that ending in June 1996. It was written for serialisation at the express request of a former Daily Telegraph editor.

So the old wizard has done it again: a joyous, entertaining three-card trick during which the rabbit goes back into the hat from which it had only ever cautiously peeped. If you want to learn what really happened, privately and professionally, to Alec as a young man you have to read between the apparently innocuous lines of Blessings in Disguise. This time around, the problem is slightly different: 1995-96 seems to have been a curiously uneventful year for one of our three greatest living actors (Scofield and Gielgud, who else?), and so, instead of skirting round the trickier eventualities of his life, the author has had to invent some, in order to kick-start the diary into any kind of lively chronicle.

About the disappearing act, we should never be so surprised: Sir Alec first perfected his screen technique in a run of Ealing Comedies which became famous not so much for his appearance in them as for his disappearance into their leading characters – sometimes about half a dozen of them, as in Kind Hearts and Coronets. In life, as in work, Sir Alec has resolutely refused to come out as anything even faintly resembling himself. One of the recurring themes of the book is his irritation when yet another army of overseas fans send him Star Wars stills to be autographed. Sir Alec, torn by the desire to be well-mannered but reluctant to return them with the useless foreign stamps reaches no satisfactory conclusion. My father, the actor Robert Morley, had the same problem. Only in the very last year of his life did he dare to chuck them in the bin, and, luckily, Sir Alec isn’t there yet.

Guinness writes self-deprecatingly of being ‘at eighty-two well past my sell-by date’, but then realises that he will have to start doing something, if only for the diary. He sees his life in terms of a general, gentle decay and is especially worried, for no good reason, about his feet: ‘crumbling sandstone monuments, their soles criss-crossed with ancient, indecipherable runes which probably hold the secrets of eighty years of living and partly living – of happiness and fears, of distresses, of rather embarrassing successes and expected failures’. And that, on page one, is about as close as we get to any real revelations.

There was once a story, probably apocryphal, about Ivor Novello, who, apparently, in the year of his death, achieved a quite remarkable if eerie claim to fame. Friends would take cheery photographs of him in the midst of others, only to find, when they got their prints back from Boots, that Ivor had disappeared, leaving an empty space where the middle of the picture should have been.

You feel that way about Alec’s diary: he has somehow managed to disappear into the middle of it. True, he is not (unlike his friends, John Wells and Alan Bennett) a natural raconteur, gossip or journalist: indeed, one of the moments of predictable public embarrassment is when he is asked to give a ritual speech to a gathering of booksellers at the seaside and finds he has nothing whatever to say to them.

Elsewhere, like most of us, he seems to sit around a lot cursing at the telly and the newspapers, worrying vaguely if he ought to be doing something more constructive, before settling back into irritable grunts about the obituaries: ‘Death has [taken] John Osborne, Fanny Cradock and Peter Cook … all regrettable, but the theatre did not begin with Look Back in Anger, Cradock’s cookery appeared to me over-elaborate and ill-tempered, and Peter Cook’s obituaries took up more press coverage than would the assassination of the Royal Family.’

Bennett, asked by Guinness to explain the latter phenomenon, notes icily that ‘Cook was a journalist’, which seems a bit rich coming from somebody who is more of one than Cook ever was. But soon we are into Christmas reading-lists, amiable lunches with theatrical widows at the Connaught; Sir Alec and Sir Dirk seem forever to be occupying different ends of the same restaurants or shops or Chelsea pavements, two wary old birds keeping a distant eye on each other for signs of what? Old age, a job, a peerage? We are never told.

Soon, however, he realises that simply offering up random comments on the papers, the television and his friends will not quite fulfil the terms of his contract; a little, light travel writing ensues, and he manages to get himself electronically stuck in the luggage car of a new French train. Then Sir Alec takes himself back to Eastbourne, consciously seeking out childhood and schoolday memories which resolutely refuse to come back.

The careful reader will detect some old animosities: his David Lean obituary is forgiving but not forgetting, and there’s a passing reference to Sir David’s ‘deadly’ A Passage to India which was the cause of their fall-out after a lifetime’s partnership.

Commendably, Guinness doesn’t seem to think any better or worse of people just because they are dead; when he loved someone like Bobby Flemyng, he writes instinctively and heartbreakingly from the deathbed before gathering himself back into his shell like an old tortoise who may have stuck out his neck just too far for comfort.

At times one feels this diary should be marked ‘strictly private’, not as an indication of what it contains, since most of it is really very public, but as a reminder of the kind of sign one imagines Sir Alec hanging Sir Alec’s neck. The careful reader will find sudden insights into what is really going on beneath that apparently tranquil surface, but in the end his diary is an odd kind of mirror, reflecting whatever happens just out of eyeline.

So why, after what must seem to him an unwarrantedly hostile review, is his the book I plan to give anyone who has not already bought it for Christmas? Because, despite all the above caveats, any Alec is better than none. We may be looking into his glass rather too darkly, but there’s a spare elegance and regret here which is captivating, even during the travelogue. His passions, whether religious or other, bubble just under the surface of the text, and my guess is that somewhere, just as in so many of the films he made about escape, deception and false lives, there is another Alec Guinness diary locked in a cupboard and, unlike Noel’s, never intended for publication. Sometimes you think he couldn’t even bear to read it himself. But read this: it will, often inadvertently, tell you something about one of the greatest and most mysterious and mystical theatrical talents of the century. Beyond that, it’s all we’re likely to get, and if we’re not all a lot politer about this slim volume than I have been here, then we may not even get another like it; the old wizard will simply have disappeared into his own smoke yet again. No wonder he was always best at suddenly materialising from some other planet; Eliot’s Uninvited Guest has called again, and it’s up to us to try and work out what he wishes to tell us.