Gilbert and George have got the plumber in. They seem inordinately pleased at the very idea, and as they usher me slickly indoors I can't help noticing a muffled frisson as George glances covertly at Gilbert and whispers something about a man, a sink and a piece of lead piping.

Not that you get to see the actual plumber in question, you understand. He's concealed behind a wall of perfectly restored Georgian wood panelling - and is actually beavering away next door, in the house they have just purchased. ''It'll be marvellous,'' enthuses Gilbert. ''We'll be able to put a door in the hall to pass from one house to the other. We'll live in the first and work in the

second.'' Prices for this type of

Georgian four-storey townhouse in Jack the Ripper's former stomping ground are currently running at (pounds) 1.2m. The iconoclastic outsiders

of the British art establishment aren't daft.

There isn't time to stop as they march me clumpily down their uncarpeted narrow hallway, through the back door, across the snow-

covered courtyard and into a freezing storage room. They take my coat. I can see through to the adjacent, brightly-lit studio and see one solitary chair facing two. Clearly they've been preparing for this visit, although when I'd rung earlier they'd bid me a distinctly pert ''goodbye and good riddance'' via their telephone answering machine. What the hell was I letting myself in for?

Any visit to the ABAs (Ageing British Artists) was bound to be a bit weird, but this is plain surreal. Before we've even finished shaking hands they've claimed to be the ''most disturbed'' people they know, and more avant garde than any YBA like Damien or Tracy or Graydon. (''Look! This is our spunk! Our piss! Our blood! We were doing this 20 years before them!'' says Gilbert, as he rifles through one of several hand-made catalogues of their early work. Bodily fluids and solids are photographed from microscopic slides.)

Things get worse when George suddenly commands me to guess the identity of a weird-looking shape with legs that has been digitally superimposed over brand new artworks propped up along the walls of the studio. ''Guess what it is!'' he invites. ''Oooh, you can't tell?'' He claps his hands like a 62-year-old child. Gilbert joins in and, sensing

a descent into Kafka territory, I

hazard a wild guess. ''A cockroach?''

''Try again!'' they chorus.

I give up.

''It's a pubic louse!'' they reveal triumphantly. Ah. The louse is apparently one of George's, acquired personally because the Department of STDs refused to supply one even though he needed it for his art. However, for all their shock tactics (their work uses profanities like c***, s***, f***, poof and cock) Gilbert and George are all smiles and suits and impeccable good manners in real life. The Living Sculptures insist they never swear.

''That telephone message is only meant for the 10% of people who know who they are,'' says George cryptically in his Home Counties accent. Gilbert, who is Italian, starts to giggle. George adopts an attitude of avuncular indulgence. He offers me a coffee, ''instant, of course'', and doesn't even need to wait for the

kettle to boil. It's there already.

The coffee is out of a catering size tin of Nescafe. ''We never shop,'' they trill proudly. ''We buy 24 tins like this at a time, and 500 loo rolls, from a local cash and carry. It's much cheaper!'' Gilbert adds: ''And it saves so much time.'' Neither do they cook or have a kitchen. A shiny electric kettle in the studio is all they have. George says they brought it out specially for me. ''You have so much more time if you don't have to shop or store food or get rid of waste food, or boil or bake. Nothing,'' he states magisterially.

They have spent every day together since meeting at art school in 1967. What do they need so much time for? ''To make pictures!'' cries Gilbert. They are due to deliver 24 new works, each four metres high, by June for a commercial gallery in Paris. The exhibition will be called East One, and will comprise images of East End street signs - with the boys included, of course. Names like Dunch Road, Cressy Lane, Calvin Street, Martha Lane, Gun Close read like a soon-to-be-lost social history. ''We love these names,'' says George. ''They are like a future landscape. They will be there long after us.'' Do they hope for a Gilbert & George Street? ''Mmm, though it'll probably be an alley,'' he smirks.

They have never sold a picture in Britain. How do they feel about Charles Saatchi buying a painting from the former stripper Stella Vine? ''We don't know her. Saatchi never bought us,'' says Gilbert frostily. ''We never fitted in. We are established, but we are not establishment. We've realised it's quite good not to be involved.''

What about their much longed-for retrospective at Tate Modern? ''We are in secret negotiations with the Tate as we speak,'' says George. ''The trouble is we don't want Tate Britain. If it comes off we will be

the first to break the apartheid

system which dictates that British artists can't show at Tate Modern, which we strongly disapprove of. Why should our contemporaries around the world be allowed to show in the superior space? We'd rather come to the Scottish Gallery of Modern Art.''

Ordinary details about ordinary lives are what make G&G tick. They say they merely observe and wish

to include rather than exclude. Although they live an almost hermetically sealed life away from the hoi polloi of nearby Brick Lane and Spitalfields Market, they seek out seediness in order to make their

art. They don't live it: they merely photograph it, then salt it away for future reference.

To this end, they walk a lot - to dinner every evening at a Kurdish restaurant some miles away in Stoke Newington. George leaves the house at 6.30pm and walks for an hour and a half. Gilbert does it differently. ''I only do 45 minutes because I have the flat feet and they hurt after a time,'' he explains a touch petulantly. So he leaves the house at 7.15pm, meeting up with George at 8pm. ''Our walks to

dinner serve a triple purpose,'' says George loftily. ''To eat, to keep slim and to harvest our material.''

But doesn't separating mean they might see different things en route? ''Ah . . .'' fumbles Gilbert. ''We share what we've seen over dinner,'' clarifies George. ''It keeps us enthused.

''We're two people, but one artist,'' he adds neatly. Or, as someone else once said, like two buttocks of the one bum. ''We don't even know which of us took what picture. It's totally irrelevant.''

They describe their relationship simply as ''everything''.

An entire wall of the studio is covered in carefully made charts showing which photos are contained in the box files sitting underneath. These include such subjects as Pussy, Mobiles, Smiley Faces and Toilets. Gilbert shows me another set of cardboard boxes which contain tiny scale models, with contents, of every single European exhibition they have ever put on. He takes me to a wall of grey steel cupboards and, with a Latino flourish, opens one of them to reveal pile upon pile of neatly annotated, flat, brown cardboard boxes. ''We believe that it's good to keep everything. We have every personal letter and invitation card that has ever been sent to us.''

Why? ''Immortality is not easy,'' explains George. ''We want to speak from the grave.'' Is it good to be so organised? ''It is necessary.''

I ask to see their home. The narrow four-storey house is silent and gloomy. It's also breathtakingly beautiful. There's original floor-to-ceiling oak panelling, moulding, stripped floors, bakelite switches, stone fireplaces. Gilbert confides that they did all the restoration themselves when they bought it 30 years ago. What? They actually messed up their trademark bespoke suits with Nitromors? ''Ah, but we put on our overalls over them!'' he replies, showing me a pair of navy drill coats on a hook.

The further we climb up the wooden stairs, the more fantastic it becomes. The smell of mothballs becomes stronger as we enter the first living-room. There are two heads of Christ, a crucifix, a massive Bruce Talbot dresser, tables and countless nineteenth-century vases.

Upstairs again are two fabulous cabinets by the Scots designer Daniel Cottier. Ancient candlesticks made by church architects sit on oak tables. There are many vases by the Glaswegian artist Christopher Dresser. ''We're great admirers of

the Aesthetic movement,'' explains George. There are so many vases they begin to resemble a silent ceramic audience.

Don't they need an awful lot of dusting? ''Ah, but we have a very nice man who comes in once a week,'' says George. You feel he - and just possibly the plumber - must be the only visitors to this priceless paeon to the past.

Back on the ground floor, the original kitchen contains only a sink and a few Duralex tumblers on a shelf. The shutters on to the charming back yard are closed tight and I feel a great urge to rush over, unbolt the original fastenings, throw open the window, and fill up one of their huge vases with flowers. Gilbert chides me. ''We do not have cut flowers in this house. If we want to look at plants, we go to Kew.''

They certainly don't look at the work of other artists and haven't been in a gallery for yonks. ''We don't want to see what they are doing, and we don't want them to see what we are doing,'' explains George. Or was it Gilbert? ''People will understand our work one day.''

I found their self-obsession to be strangely suffused with sadness. Whether that sadness is for themselves or for the plight of humankind in general, it's difficult to say.

Gilbert & George - Obsessions and Compulsions, Robert Dutt, Philip Wilson Publishers, (pounds) 25.