Three and a half years ago Barnes succeeded Clive James who had wriggled, writhed and dozed in his fabled armchair since 1972. James is often thought of as the man who brought TV criticism into the present century. He filled his columns with his customary humour but also imbued them with a multi-browed appreciation which corresponded to the diverse output emanating from the box itself.

Like James, like most TV critics, Barnes came to the post in a haphazard manner.

"I would think it very odd if people left school or college saying 'I want to be a TV critic'," he says, perched beside his typewriter in a tasteful room in a tasteful house in a tasteful part of north London.

"In a way it's a job that everybody thinks they can do and everyone is equally qualified because they all watch television. I happened to be working at the New Statesman when the TV critic failed for the umpteenth time to deliver his copy, so I filled in for a few weeks and ended up doing it for two years. Then I had a year off and went to The Observer."

With the springs of that Observer armchair shaped and moulded to the frame of James over a decade, might Barnes have found the sect a little uncomfortable to begin with?

"I knew I could do the job and The Observer knew I could do the job because I'd done it before. But inevitably with someone as hugely popular as Clive you're going to get letters for a long time saying 'who is this man? Bring back Clive James' (and that's just from Clive's mum). But that's just about dried up now.

"Most readers of newspapers don't read bylines, that's the great mistake journalists make, thinking people know that they've written stuff. But for the first few weeks I tried to make if as unlike Clive as possible and thereby it was a bit unlike what I normally did. I tried to cut down the jokes (laughs)."

And now the jokes are back ...

In Julian Barnes' bathroom stand two large piles of TV and Radio Times. A saving on toilet tissue is guaranteed but with such an abundance of material available how does he decide what to watch?

"You consider that readers of The Observer will be interested in certain programmes more than others and there are 'big' programmes that have to be reviewed. Beyond that it's a column with its own nature and interests from week to week. You're allowed to include your interests to a certain extent but obviously you mustn't go over the top and write about chess every week. It's a case of what the readers will be likely to watch and what the 'big' programmes say about television. I don't get a diktat from the upper floors of The Observer."

He's never counted the hours per week he gazes of the screen but owns up to watching many "bits".

"I button push a lot. I think that's what normal viewers do anyway. Behaving like a normal viewer is, I think, the way to do the job. Or at least that's how I do the job. The other sort of TV critic is the corridor pounder who always knows exactly what's going on at the BBC, gets excited when someone moves from, say, Granada to BBC2, and knows the people who make the programmes. I just sit at home and watch."

Do the programme makers pay heed to the critics?

"Very rarely. Usually the programmes have been made some time ago anyway and the makers have moved on to the next project. I think the critic should assume that their word carries no weight at all otherwise you get into a state of preening self-importance. Occasionally things will happen to encourage you in the fallacy that your word carries some weight.

"For instance, when Bernard Falk was doing the unlamented Sin On Saturday two years ago. I watched and thought 'I've seen bad but this is dire' and I rubbished it and noticed everybody else rubbished it, There were two weeks of constant rubbishing from the critics. Then Bernard Folk was taken out at dawn and shot.

We all thought 'oh, the power of the critic'. It's much more likely that Alastair Milne who had just been appointed Director General decided to shoot someone to encourage the others.

It doesn't mean that programme makers are impervious to criticism but they go more on audience figures than what the critics might say."

I ask whether television is a good and stimulating thing at the present time. Barnes takes this to mean I don't think it is but, in fact, reeling from a mesmerising brace of East Enders episodes and a video so full that I don't have time to watch ail the contents, I mean the opposite.

"I think television is always in the same state more or less. I remember Dennis Potter one time being asked what it was like working in the golden age of television and he replied 'we thought it was the silver age' – the golden age was always just over the horizon. The trend is to look back at earlier television eras and think they were jolly good when in fact they were rather worse than what you have now.

"The advantage of now is that Channel 4 is very interesting and I often find that half the things watching are on C4. But that has been brought about BBC2, which used to be the minority channel, going downmarket at a rate of knots over the last few years. I don't think there is anything to be exceptionally gloomy or cheerful about."

And musical action? The JB column steers clear of the likes of The Old Gruel and The Tomb.

"I very rarely see them. I must disappoint your readers in that respect. I'm afraid my Top of the Pops period was some time ago" (how very disappointing – ZZ subscriptions dry up).

Not so long ago satellite and cable were spoken a being the bright new future of British broadcasting. Pavements were hacked up with vigour and vast saucepan-like objects appeared on a few roofs. The glee suddenly subsided.

"Yes, I think we lead the world in television failing, which is a good thing to do. The cable revolution so far has been a complete failure over here. To spend £200 a satellite dish or on cable rental means the television has to be of very good value. The main television channels have got such a stranglehold on the big events like the cup final etc that no government in its right mind would hive off those to cable or satellite companies.

"The government seems to have gone quiet on that aspect of the Sunshine Industries front. Perhaps we don't always do tomorrow what America does today."

When will that lurid flicker from the corner of the room be a pain rather than a pleasure? Will he one day hang up his notebook, slash the armchair and book into a penthouse suite solely to sling the TV set out window? When will his palate be jaded?

"It depends how long they want me. I'm on a yearly contract renewed every June or July. I still enjoy it and I think you should always get out before you find yourself going stale – whether you know you're stale is another matter. But I've done it for three and half years, Clive James did it for 10 which makes me envious of his stamina. I think he was just as good at the er he was at the beginning.

"I think it'll be determined by my deciding I ought to up the column and then I'd look around for some other kind of journalism. There's nothing more miserable than seeing a critic going through his paces when got nothing to say. They are about, journalists with names I won't mention while the tape is still running."

So I switch it off and, revealing my true identify, demand to see his TV licence.