SANDRA Kerr has been a hero of mine for more than a quarter of a century. She doesn't know it, of course, but then, until recently, nor did I.

The reason is that Sandra was one of the stars of Bagpuss. Not one of the real stars, mind you, they were the puppets, naturally, but one of the voices behind the stars. Her part was Madeleine, the rag doll who dispensed wisdom at appropriate moments and kept everyone else in line. She also co-wrote and performed all the songs and the theme music. But, by far her most important role was to contribute towards the voices of the mice - they of the marvellous, mechanical mouse organ - who were the real centre of attention, whatever that saggy old cloth cat might think.

Even though it ran for only 13 episodes, each lasting just 15 minutes, Bagpuss became one of the most loved children's programmes of all time, regular repeats ensuring it captivated an entire generation. Three years ago, it was voted the most popular children's TV show of the last 50 years, beating the likes of The Magic Roundabout, Play School and Mr Benn. So I'm obviously not the only one.

But then meeting your childhood heroes can be a sobering experience. Almost inevitably there is disappointment as you find they do not, probably cannot, live up to your sepia-tinted memories. As she makes coffee in the kitchen of her semi in the Northumberland village of Warkworth, Sandra asks if I know that part of the world. When I tell her I had been at nearby Alnmouth the previous weekend, she almost tells me off for not calling in for a coffee, and I'm sure she means it. I think my memories are pretty safe.

Already a distinguished folk musician, her life took a new turn in 1974 when a producer she had worked with suggested her name to Oliver Postgate, creator of The Clangers, Ivor the Engine and Noggin the Nog, when he was looking for people to contribute towards a new programme, and she was invited down to Postgate's home in Kent.

'He is not messianic, but obviously very caring, and I think that shows in the Bagpuss programmes, that whole idea of mending, reusing and recycling. Even though those words aren't used, that is what the programmes are about - seeing what can be done with something that looks like you should throw it away."

It was this ethos, where the characters - Bagpuss, Gabriel the toad, Madeleine, Professor Yaffle and the mice - see what they can do with the broken toys Emily brings into the shop, that convinced Sandra to take part and overcame her natural wariness of mass-market television.

As well as voicing Madeleine, Sandra wrote and performed all the songs, along with musical partner John Faulkner, and the film would then be cut to the music, rather than the more usual other way around. For the mice, they would sing high slowly and then their voices would be speeded up.

"We were full-time musicians, we had a background in traditional folk, but also blues and things like that. The fundamental aspect of traditional music is improvisation, plus the fact that it was such fun, and if it's fun it doesn't feel like hard work.

"To be honest, we were a bit messianic about traditional music in those days, and to have any truck with the media felt a bit of a compromise. But I don't think we realised what we were doing. I don't think we were quite aware of how important to people these programmes would be."

The impact of Bagpuss was brought home when Sandra and John, along with Sandra's daughter Nancy and Nancy's partner James Fagan, took Bagpuss on a nationwide tour earlier this year. After one show in Leicester, a 30-something dreadlocked man came up to Sandra and said: "Madeleine, you have been my mother for years."

"People have very fond memories of it as an integral part of family life. It was a time when people watched television with their children, and I think the warmth of the characters is enormously important. It is sobering when you realise how important these characters were and what a responsibility it is," she says.

Of course, some fans take it all a little too seriously. Websites have been created devoted to analysing the characters, with Madeleine coming out as an Earth mother type. This seems entirely in keeping with the musician in front of me, but Sandra is not so sure. "I just think they were warm, funny, engaging characters, and if people see more in them, then I don't think that is too dangerous."

She admits the adoration of Bagpuss devotees is a little unnerving, and not at all what folk musicians are used to. But while that cat may have given her a level of veneration unheard of among her contemporaries, it is a double edged sword.

"I have been a professional musician for over 35 years, I have written dozens of songs on social issues, I have taught and run choirs and travelled all over the world, and what really gets you attention is something that has been on television. That is what impresses people.

'That is not to say that I don't think Bagpuss is valuable, I value the work I did on it, but when I think of the time spent doing other work, which I think is important...", she tails off, but if Bagpuss has overshadowed the rest of her career, there is no trace of resentment, just a kind of wistful acceptance of the way things are.

"I just think it kind of reinforces what I feel," she continues, "that our society seems to value the mass rather than the small, the local, and that is slightly distressing. I'm glad it was for Bagpuss, which I do think counteracts it slightly, but on the other hand, there are so many fine musicians and singers and writers who will never have the attention they deserve."

This leads neatly on to the latest twist in her musical career. At 60, she has embarked on a new phase, as a lecturer in singing on the Traditions of these Islands course at Newcastle University, which started last year. Although she has always been involved in workshops and teaching, this is a chance to nurture a new generation of folk musicians.

"It is a highly complex and beautiful and time-honoured art form - we should be proud of our tradition. I do love to teach, and I enjoy the process of introducing people to ideas. And I can't say how important it is to have a degree course in an art form which has had a bad press, or no press at all."

She obviously has mixed feelings about the status of folk music - feeling it has been unfairly neglected, but knowing that if it had mass appeal it would inevitably lose much of the diversity which makes it what it is.

But, for her part, she can take comfort in the fact that while much of her work is unknown to the mass market, her contribution to Bagpuss means there is a bit of folk music in a lot of people.

She is also, I might add, one childhood hero who won't let her fans down. As I leave, followed by her two cats, one of them ginger, she says that whenever I am in the area I must call in. I'm sure she means it. It's only as I start the car that I realise I've forgotten to ask what the cats are called. It would be too much to hope, wouldn't it?

l Sandra Kerr is appearing at the Composers Club on Wednesday, September 11, at the Bridge Hotel, Castle Garth, Newcastle, from 8pm.