A very senior media executive once told Humphrey Carpenter’s widow: “I would never advise anybody to have Humphrey’s sort of career."

Humphrey's was a quite extraordinarily varied and — had it been anyone else’s — exhausting working life.

It will be commemorated tomorrow, three years after his death, with the unveiling of a stained-glass window at the St Margaret’s Institute in Polstead Road, North Oxford.

People met Humphrey in a variety of ways. There he was on air during the earliest years of BBC Radio Oxford in the early 1970s; then three decades later on Radio 3 or Radio 4 — one moment dealing with listeners’ music requests, the next presenting a programme about Arthur Conan Doyle (I declare an interest — I produced that one).

You might have picked up his first biography — that of JRR Tolkien in 1977 — or his last, about the publishing house of John Murray, on which he had been working at the time of his death in January 2005, and which came out earlier this year.

Children of any age will have rejoiced in his Mr Majeika books.

Perhaps you saw him as a member of the Park Town Strutters — appearing jazz-wise at venues all around Oxford — or fronting his own dance band, Vile Bodies, during its residency at the Ritz Hotel in London in the late 1980s (this gig was very important to him — anyone else who wanted to call upon his services during this period really had to hit his diary early on).

Very specifically, you may have been a member of, or seen a production by, his children’s drama group, the Mushy Pea Theatre Company.

That’s where the St Margaret’s Institute comes in, for it was there that Humphrey organised their regular rehearsals.

"Mushy Pea came about for a couple of reasons," remembers his widow, Mari Prichard.

"Humphrey always said that one of his most formative influences when young came from being a member of the Dorothy Cordon Children’s Pantomime Society in North Oxford — that’s where he first learned to get laughs and he recalled its anarchic influence.

"Then a Welsh cousin of mine turned up in Oxford from London with his two children, and one of them had been attached to some sort of amazing drama group that didn’t exist here. Humphrey, being Humphrey, immediately said, 'Let’s do it!'."

The Mushy Peas took on children from the ages of five to 18 and Humphrey rehearsed them at the institute every Saturday afternoon, with an emphasis on improvisation and, vitally, an assumption that no child should necessarily be expected to be able to read any text.

Mari remembers lots of noise and wondering how anything controlled could possibly come out of this apparent chaos.

But they put on shows at The Theatre, in Chipping Norton, and, triumphantly, at the Shaw Theatre in London in 1993. Productions included The Twiglets in Trouble, The Wizard of Oz, Alice in the Channel Tunnel and Mr Majeika — The Musical.

A year ago, the institute’s committee met for a specific purpose: to discuss a memorial to Humphrey Carpenter.

Elisabeth Salisbury, of Kingston Road, North Oxford, told me about the project. "Humphrey was always doing things in the institute, not just the Mushy Peas. I remember jazz evenings and talks: he was a much-valued member of the community and we were all pretty devastated when he died so young. We approached Mari, and she was absolutely convinced that she didn’t want any sort of seriousness: it had to be something that would express his joie-de-vivre."

Mari Prichard shares that memory: "They asked if I’d mind! And I said 'Of course not!' Maybe I was a little churlish, but I did say that I didn’t want anything that looked like the sort of memorial I remember from my childhood — you know, plaques on the chapel wall. I think I was being a difficult widow, trying to relay that the shade of Humphrey wanted everything to be entertaining, not boring."

Elisabeth Salisbury told me what they wanted.

"The idea was for something artistic that could go into the main hall. A sculpture would have been too dangerous and there isn’t much space on the walls to hang a picture. One of the lovely things is that the window will be west-facing, so that in the afternoon the sun will come through and shine on the floor and decorate the rest of the room just as much as the window itself.

"We raised a lot of the money by some local North Oxford residents opening their gardens in June, but dribs and drabs are still coming in — and we’d like some more!"

The commission went to local artist Susan Moxley, who had impressed by creating some stained glass windows for the nearby St Philip & St James Primary School.

In her studio at the bottom of her garden in Oakthorpe Road, she showed me the final product — which was in four pieces at the time.

There had been no specific brief other than to celebrate ‘the magic and energy which he gave to his work and the children’.

It was very important for Susan, as an artist, to visit the Carpenter house and, of course, meet Mari Prichard.

"I also read his Majeika books and realised that words and sounds were as important as the visual imagery."

Susan, married to popular Oxford children’s artist Korky Paul, trained in South Africa, going down the art route when she was found to be dyslexic.

First and foremost, she draws. Now, the medium of stained glass appeals to her.

The thinking process for this project, she said, took many weeks, and the practical work (drawing to scale, painting, glass-cutting and soldering) two months.

She decided that Humphrey’s silver bass saxophone should be the central image of the piece, together with a jumble of letters pouring out of it and a beanstalk recalling the Mushy Peas.

For the border to the sax, she has taken words from the Majeika musical — "I am the magic man, come follow me and you will see how wonderful the world can be".

"This perfectly expresses the energy that he gave to performances," Susan told me: "I am also glad that I chose the words to be in the present tense — he continues to be the magic man!"

She has also found room on the glass to pen the words ‘directed by Humphrey Carpenter’ — a clever touch.

The saxophone theme was taken up by the writer, broadcaster and musician Russell Davies, a long-time friend of Humphrey, who presented a Radio 3 concert in his memory from London’s Cadogan Hall in 2006.

The big bass sax was actually taken up to the capital for the occasion.

"I love the idea that Humphrey is being represented in this way," Mr Davies told me. "I felt proud that it was after a TV programme of mine — a history of the bass sax called The Lowest of the Low — that he went out and bought the instrument.

"After his death, visiting his house, it was the first thing you saw, standing in his vestibule, and I felt it was symbolically him — of striking and dignified appearance, yet unmistakeably a source of comedy: deep and fundamental, but capable of frivolous flights in any direction."

Humphrey Carpenter died of a heart attack. But for some years he had been suffering from Parkinson’s disease. He had been dealing with that situation — as anyone who knew him would have expected — with humour. He had been working on a one-man show about his illness, called — with typical Carpenter flair — Shake It All About for the Edinburgh Fringe ("not so much a stand-up as a fall-down show", mused Mari), but that did not happen.

At his funeral service at St Barnabas Church, in Jericho, a hint was given of what he had had in mind, followed by a commemorative event at the Oxford Literary Festival at which a couple of his Shake It All About songs were performed.

There was a sell-out fundraiser at the Oxford Playhouse in support of Ann McPherson’s Witney-based DIPEx charity website helping and advising on various illnesses and diseases when much more of Humphrey’s work-in-progress was actually progressed.

Now his legacy is about to be firmed up, with a presence on the DIPEx Parkinson’s disease module on www.healthtalkonline.org being launched on October 13.

And the Oxford Literary Festival launch next year what’s hoped to be a regular 'Remembering Humphrey Carpenter' event, when teams from local schools will spend a day working on an improvisation project, and then perform at the Burton Taylor Studio at the Oxford Playhouse. It is early days, but note the date of Saturday, March 28, 2009.

Meanwhile, from tomorrow, three years and eight months after the death of Humphrey Carpenter, there will be a permanent and tangible memorial in the form of Susan Moxley’s vibrant glass creation.

You don’t have to be an old Mushy Pea to raise another sort of glass in memory of a true Renaissance man.