I watched the first episode of 'The Singing Detective' in London, when it was broadcast for the first time on the BBC in the autumn of 1986. It took not very many seconds to conclude that I was watching the most extraordinary piece of television that had ever been made.

This is from the screenplay: "A misty, moody, highly atmospheric 'thrillerish' winter's evening in London, 1945. Cold and forlorn, near a lamp-post which dimly shows wisps of mist, a pathetic old busker is playing an achingly melancholy 'Peg o' My Heart' on a mouth organ. This seems odd: there is no one about. The music takes us along the empty street."

From a door marked, in neon, 'SKINSCAPE'S', a doorman appears, dabbing at his mouth with a handkerchief.

"MARLOW: (Voice over) The doorman of a nightclub can always pretend that it's lipstick and not blood on his hands. But how'd it get there? Let's be economical. Nothing fancy. If he smacked some dame across her shiny mouth, then he's got both answers in one."

'Singing Detective' isn't one of those anaemic pieces of work Hollywood keeps churning out, with pretty boys as detectives and scripts that probe Kermit-the-Frog-deep into the human psyche. Raymond Chandler wrote better stuff. The first sentence of 'The Big Sleep', for example, "It was about eleven o'clock in the morning, mid October, with the sun not shining and a look of hard wet rain in the clearness of the foothills," is pretty hot stuff. But 'The Singing Detective' is right up there at the same sort of altitude.

Back in the 1980s, the BBC was seriously interested in getting it right, and they certainly did with this screenplay. They followed the script as if they'd had it from Moses. They cast Michael Gambon as Marlow, probably the most successful piece of casting since Fritz Lang used Peter Lorre in 'M', as Hans Beckert, the child murderer.

Gambon's a big guy, as Marlow should be, with the face of someone who's been around. He has a certain gravity … the dignity of a man who knows more than he cares to. He is the perfect Marlow, and the BBC took care to use gifted people to support him.

'The Singing Detective' is more than just a whodunit, it's as serious and as complex a drama as anything in literature. It works in three layers. The first is the story of Philip Marlow, a man in hospital with the worst kind of full-body psoriasis (actually psoriatic arthropathy, which attacks both skin and joints), which is killing him emotionally, and perhaps physically. He writes whodunnits for a living, so the second layer of the drama is the book he's writing, in his head, to get away from the ugly reality of his situation, the book that starts outside 'Skinscape's' (get it?) on that cold winter's evening in 1945.

Marlow's schoolboy memories, of a childhood spent in the Forest of Dean (one of Britain's few remaining ancient forests, on the borders of Wales and Herefordshire in the western part of Gloucestershire) in the 1930s, make up the third layer, leaching constantly into the first and the second.

It was not a happy childhood. He loved his singer father deeply, yet hated him for not being able to control his serially unfaithful mother. His father's songs and other jazz and popular music of the period are used extensively in the plot, to pivot and to bridge, to underline and to provide comic relief.

The six-episode 'Singing Detective' lasts for six hours and 42 minutes, and there isn't a wasted moment. It is an outstanding work, written by a master. The British Film Institute says its author, Dennis Potter, is "one of the most important creative figures in the history of British television". I don't know why they limit it to British television.

Dennis Potter is an ex-journalist who worked, once directly and then as a free-lancer, for the BBC, writing scripts. He constructed a personal body of work of such remarkable depth and range that it can't be touched by anyone else working in television. American television writers and producers worship Potter, saying he inspired them to create such series as 'Hill Street Blues' and 'NYPD'.

The Film Institute says he is the "most prolific yet also most controversial of television playwrights, he remains the undisputed figurehead of that peculiarly British phenomenon of writers who expend much of their working lives and passions attempting to show that television can be just as powerful a vehicle for artistic expression as cinema or theatre.

Attempting, and succeeding. It won several awards, and was the only piece of television ever screened at Joseph Papp's Public Theatre in New York, as I recall. But television is thought of as film's poor cousin. Had it been made as a movie, it would have won every award ever offered.

'Singing Detective' is very much taken from Potter's own life. In his mid-twenties Potter developed Marlow's disease, psoriatic skin irritation, which left him drug-dependent for much of the rest of his life. His childhood was spent in the Forest of Dean. Marlow's parents are like Potter's own.

And, subtly, there is a part of 'Singing Detective' that describes Potter's love/hate relationship with Christianity.

The novelist Julian Barnes believes that Potter's work must be read as that of "a Christian socialist with a running edge of apocalyptic disgust". His writing can only be properly understood as a rant against a faith he loathed, but could never escape.

"We live among the litter of religion," Potter's said. "It's part of our culture, part of our instincts ... In illness I pray, even if I simultaneously disown the prayer. We cannot deny Christian feelings, or, at any rate, feelings inherited from Christianity."

In 1994, Potter was diagnosed as suffering inoperable cancer. After having been given three months to live, he wrote, and finished two linked TV serials, 'Karaoke' and 'Cold Lazarus'. He died on June 7, 1994, nine days after his wife, Margaret, died of cancer. In a television interview that took place a few days before his death, he said: "My only regret is if I die four pages too soon".

At one point in 'The Singing Detective', Marlow says: "The rain falls. The sun shines. The wind blows. And that's what it's like. You're buffeted by this, by that, and it is nothing to do with you. Someone you love dies, or leaves. You get ill or you get better. You grow old and you remember, or you forget. And all the time, everywhere, there is this canopy stretching over you…"

www. pondblog.com