Oh yes, we remember them well...

I'm not sure what it is about this time of year, and in particular the grey sag between Christmas and New Year, but it always seems to bring its crop of departures. Perhaps it is, as John Donne wrote in "A Nocturnal upon St Lucy's Day", that "the whole world's sap is sunk;/ The general balm th' hydroptic earth hath drunk,/ Whither, as to the bed's-feet, life is shrunk,/ Dead and interr'd". (He clearly knew something about seasonal affective disorder, Donne).

Maybe the old hospital wisdom about terminal patients making it through to Christmas on sheer willpower alone has something in it. Or perhaps there just isn't much else for newspapers to write about and so deaths that might normally be part of the general landscape of mortality achieve unusual prominence. Whatever the case, you can safely bet your leftover turkey that the orts of December will deliver a sheaf of showbiz obituaries. This year, Alan Bates and Bob Monkhouse were the headline acts, with Dinsdale Landen and Patricia Roc posthumously upstaged.

It was sad to hear about Alan Bates and Bob Monkhouse because neither was ready to stop working - however difficult their illnesses made it - and both were still working well. Quite often, though, it's only an empathy for the bereaved that makes these announcements distressing. Audiences are callous organisms, and their relationships with stars are almost always more take than give. I can't be the only person self-centred enough to have thought, when hearing of the death of some long-retired Hollywood veteran, "Oh good - now we'll get a retrospective season of the best films".

In fact, in quite a lot of cases, death can restore a performer's vitality like little else. Fred Astaire may have been a poor shadow of his youthful self when he died in 1987, but when his shadow danced on screen - in the re-runs that commemorated his passing - he was young again. And though this kind of presence was a poor substitute for those who really knew him, for those of us who'd only ever encountered him on screen, it really wasn't a substitute at all.

Something similar is surely true of Patricia Roc - at best a cinematic footnote for anyone born after 1963, when she retired from acting - but now, at least for the duration of the news items about her, revived as "the Goddess of the Odeons". Perhaps someone will dig The Wicked Lady or Millions Like Us out of their back catalogue, and we can see her in her glory days for ourselves.

We won't ever see her as her contemporaries did, though. Because the assumption that film actors (and TV performers) achieve a technological immortality unavailable to others isn't entirely accurate - even if it looks as if they have the advantage over stage actors. On the face of it, Alan Bates's performance in John Schlesinger's film A Kind of Loving is available to us in a way that his performance in the premiere of John Osborne's Look Back in Anger isn't. One has disappeared into a fog of myth and hindsight, while the other is still there in black and white, playing out, frame for frame, as it first did in 1962. The only problem being that it isn't 1962 any longer, so we can't possibly reconstruct the freshness of seeing Bates without the preconceptions that his later career created. Watching him in A Kind of Loving, you know that a naked Oliver Reed lies in wait a few years in the future - and that can't help but affect your viewing.

A classic movie performance can still affect the audience - sometimes profoundly. It may even stir similar emotions to those it did originally. But it can't do so without in some way being a period experience. You watch in the knowledge that this is a fleeting moment artificially prolonged - whether because it shows you a performer in his innocence, or because various historical accidents of style have accreted around it. You watch A Kind of Loving with half a mind on what counted as realism in the early Sixties, how certain camera angles have gone out of fashion, and acting styles have changed.

Bob Monkhouse has it even harder, since at least part of his appeal recently lay in the way that he was renegotiating his reputation, from a plug-the-bill trouper to a sage of stand-up. So reruns of The Golden Shot or a screening of Carry on Sergeant only seal him into the kind of role from which he was beginning to escape.

In both cases, paradoxically, the best way to recover the pleasure that Bates and Monkhouse could, in different ways, generate is to go to the source least trusted by performers themselves - to the critics and journalists who wrote about them with no thought of yesterday or tomorrow, but who did try to capture what they felt at that moment. Because a talented performer doesn't really achieve his effects on a stage or film-set but in the minds of the audience. No camera can get inside there, but a good writer can, thereby preserving the most perishable elements of a performance - its novelty and audacity. Nobody ever put a statue up to a critic, in short, but they can be a good place to turn if you're after a memorial you can trust.