Both in its peculiar design and meticulous execution it provides a small but unmistakable clue that behind this nondescript Peckham facade lies the richly inventive and idiosyncratic world of the painter, composer and bookmaker Tom Phillips.
Inside the three-storey house the extraordinary nature of its owner is confirmed. The studio, crammed with works in progress, is cramped and cluttered. A collage room next door is knee-deep in torn paper. The kitchen appears to have been invaded by an army of tiny, bronze African objects and figurines, each and every one lovingly placed. The oven is long gone.
Then there's the Samuel Beckett Memorial Bathroom (the title is painted on the door with the words 'Do not paint over' painted beside them), a masterpiece of dilapidation with duck-egg blue paint peeling off the walls, a stained enamel basin and bath and a stack of yellowing, well-thumbed poetry books piled up by the loo.
'I've moved about four miles in 55 years,' says Phillips, pulling the filter off a Superking cigarette before lighting it. 'I'm very attached to south London. It's uneven and pockmarked and relatively unspoilt in one sense and ruined in another.'
Phillips is nothing if not a creature of habit. If yesterday's lunch was at the Choumert Cafe, a greasy spoon, lunchtime on Friday must mean Vietnamese. Phillips likes to eat at precisely one every day, choosing from the same four restaurants in Peckham (Saturdays are sacrosanct: always the Paris Cafe, another greasy spoon).
In each restaurant he always orders his favourite dish. 'The way I change the menu is by changing the restaurant,' he explains. 'I don't get bored.'
This morning though, his schedule has suffered unforeseen disruption. The outside world has come crashing in in the form of a Belgian curator collecting prints for an exhibition, and Phillips, though charming and obliging on the face of it, clearly doesn't take kindly to such interference in his daily routine.
Each day he gets up at exactly the same time (7am) and buys the same paper (the Independent) which he reads while eating what he describes as his 'identical breakfast' (toast and marmalade and a cup of coffee). He answers correspondence between 8 and 9.30am and then starts work in his studio, breaking for lunch at lpm. He starts again at 3, carries on until about 5.30 when he has 'a doze', goes back to work at 8.30 and continues until about 12.30, 'sometimes 'til one or two if things are going well - or badly.
'I do different things in the morning to the afternoon, and always very different things in the evening,' he explains. 'There are certain things that I will only ever do in the evenings - work on books, writing.'
The rigour of Phillips's routine is such that he felt let down when the BBC moved Radio 4's afternoon play from three to two o'clock. 'The BBC finds it necessary to upset us all from time to time,' he says. 'I used to get underway with the afternoon's work while listening to the play and now I never hear it.' (The idea of resorting to modern technology and taping it defeats him: 'I so often fail.') But ask him why he adheres to so strict a routine and he looks at you in amazement. 'I never knew anybody who ever achieved anything that didn't,' he says brusquely.
If Phillips's curious existence might look like the foibles of an old-fashioned English eccentric, it's worth remembering that this reliance on systems, structure and habit is also pivotal to his success, acknowledged next month in an impressive four exhibitions: of his paintings at the Royal Academy, his books at the V & A, his music at the ICA and his graphic works at the Angela Flowers Gallery.
He is perhaps best known for his limited edition translation and illustration of Dante's Inferno - at pounds 10,000 it is one of the most expensive books ever made, for which he even invented a new kind of paper. His work with Dante more recently resulted in what he describes as the 'ill-fated' A TV Dante in collaboration with director Peter Greenaway. The Humument, his treatment of W H Mallock's Victorian novel A Human Document, which he has been reputedly reworking for more than 25 years, became a cult classic when first published in 1980.
His portraiture - Iris Murdoch, Sir Peter Hall and Samuel Beckett being among his subjects - is also widely acclaimed (in 1989 he became only the second living artist, after Graham Sutherland, to have had a one-man show at the National Portrait Gallery), as is his music which for a long time, particularly in the late Sixties, generated more interest than his painting.
'There's almost nothing I do that I don't think of as work,' he says. 'I read for my work. When I go to the opera, that's kind of work too.' And holidays? 'There's no time. And besides, I find the beach stressful.'
Phillips admits that part of the appeal of living in south London is that there is very little to do there apart from work. 'It has no glamour, that's what I like. I'm quite weak and I'd be seduced by glamour. I'd find it very distracting.'
He says his obsessive attitude towards his work goes back to childhood. 'I can barely remember a time (that is until recently) when I was not convinced I was 'very good at art',' he has written.
'When I was nine I was astonished that Isobel Thingummy was given the art prize in the class for her version of 'A Day by the Sea' when mine had so many more people in it, and boats.
'I knew I was going to be an artist as soon as I found out you could possibly get away with doing something like that for a job,' he explains. 'An artist is a child, he doesn't have to put his toys away, can make a mess. So you carry on being a child, really. Seems like a good idea.'
Tom Phillips was born on 24 May 1937 and grew up near Clapham Junction during the Second World War. His father was Welsh and at one time a fairly affluent research chemist and pharmaceutical engineer. His mother, in her own words 'a true Cockney', ran a boarding house to supplement his father's income when he fell upon hard times.
He studied Anglo-Saxon and English literature at Oxford and, after a brief career as a teacher at a Brixton secondary school, went on in 1961 to study at the Camberwell School of Art.
Since then Phillips has basically been working and reworking the same themes. There are the solemnly beautiful 'Terminal Greys', long narrow canvasses painted each Saturday (it can only be Saturdays, the day set aside for working in oils) with the day's leftover paint, the large 'Curriculum Vitae' paintings, with words 'exploring the moments when I stumbled upon what has become my subject matter', and there's always a portrait or two on
Although the work is so diverse it seems, superficially at least, that it must have been done by more than one artist, Phillips insists on the importance of the connection between projects.
'I think of my work very much and very emphatically as one thing,' he says. 'And that's where I love it. I love the way it joins together and the whole 'one thing' that it makes.'
So a line from his treated Victorian novel, A Humument, might be used as the title of a painting; or the criss-cross patterning of the 'Terminal Greys' might appear as the background to one of the portraits.
In many ways the quintessential, if not the greatest, work by Tom Phillips is the lesser-known photographic project '20 Sites n Years'.
Every summer for the past 20 years Phillips has revisited the same 20 sites in the Camberwell area and photographed them using the same camera, the same lens and the same type of film. He stands in the same place, marking the spot with a cross, and takes the pictures from the same angle. The photographs document, in minute detail, the physical and sociological changes in his local environment.
The locations for the project are situated around a perfect circle, a half-mile in radius from Phillips's home at the time the project was conceived. .
'It's nothing glamorous, they're all humdrum places,' he says. 'It sounds boring but actually urban change, recorded in detail, is quite beautiful.'
Phillips, now divorced, takes his grown-up son, Leo, with him each year in the hope that one day he will be able to hand the project over to him and then to his children after him. (The 'n' of the title is the mathematical symbol for an indefinite number.)
Phillips may seem reclusive, but, he says, 'I think one does all of these things, as many people have said, to be loved, you know. That's why everybody does things. Eventually, I would like people to think 'there's someone who informed us about even more fun in the world than we knew about already'. That would be an epitaph.'
The motto on his studio wall, 'Es geht auch ohne' (you can get by on your own), taken from an interview with Marlene Dietrich, might also be an epitaph, although Phillips insists that despite the isolation and melancholy implicit in the quotation, he is in fact quite gregarious. 'A gregarious recluse, that's what I'd like to be called.'
Certainly, if his 50th birthday celebration at the Oval where the Tom Phillips XI took on the Rest of the Artworld (Brian Eno and various members of the Monty Python team were among the players) is anything to go by, he is not without friends and admirers.
But then the Oval is a very important place in the universe of Tom Phillips.
'Cricket's my beach, let's say. It's a very beautiful way of spending time, thinking one's doing something when in fact one isn't doing anything at all except for watching other chaps do their bit.
'It completely baffles me why everyone doesn't like cricket. There's a very special metaphor of life going on there that involves character and narrative and mystery.
'And there's always a certain unpredictable element about it. Nobody's ever right about cricket. It's just like the weather.'
Tom Phillips retrospective, Sackler Gallery, Royal Academy of Arts, 5 November to 20 December 1992.
Composers Ensemble with Tom Phillips, Institute of Contemporary Arts, 8 November 1992.
'Tom Phillips, 1972-1992, 20 Years of Prints', Flowers East, 13 November to 6 December 1992.
'20 Sites n Years' - public lecture, Tate Gallery, 2 December 1992.
'Tom Phillips: The Quest for Identity, Victoria & Albert Museum, 26 October 1992 to 8 January 1993.