...as if by MAGIC

Yet to adults of a certain age, they're as comforting as warm milk and a bedtime hug.

Memories of these 1970s Watch with Mother favourites are about to be rekindled, as two theatre companies bring stage adaptations to the Fringe. Tall Stories, the team behind the hugely popular Gruffalo, has taken on Mr Benn, while London's Soho Theatre has dusted down the pink-and-white stripey feline for a new generation to enjoy.

In the space of two days, I speak to the men responsible for both these childhood idols, and can't help being struck by how similar they are. Chatting on the phone from his farmhouse in Kent, Peter Firmin, who co-created Bagpuss with Oliver Postgate, recalls the fertile period in the late 1960s and 70s when he and Postgate also produced The Clangers and Ivor the Engine. He describes working from home with his children around him, how surprised people are to learn that just 13 episodes of Bagpuss were made, and how pleased he is with the stage production.

The following day, in London's Vaudeville Theatre, I have much the same conversation with David McKee. Best known for creating Mr Benn, but also for penning the hugely popular Elmer the Elephant series and countless other titles, McKee also recalls that era as being especially creative. He too worked from home, writing picture books and illustrating newspapers while his children played, and finds people are surprised that just 13 episodes of Mr Benn were originally shown. McKee is also happy with what Tall Stories has done with his character.

The two men also share a gentleness, a deep understanding of how important the early years are, and a work ethic that has kept them going way past retirement age. On a fleeting visit from France, where he now lives, McKee has barely arrived in London before he's talking on the radio, grabbing a quick lunch then sitting down to a day of back-to-back interviews. It would be a gruelling schedule for anybody but, at 76, he's taking it all in his stride. "That's one of the things about this way of life," he says, "you stay active."

In 2001, Channel 4's 100 Greatest Kids' TV Shows ranked Bagpuss and Mr Benn at numbers four and six respectively.One of the key elements of both Mr Benn and Bagpuss is repetition. The opening and closing sequences are comfortingly familiar, but for McKee this happened quite by chance.

"I wanted to write about a knight in armour, so I wrote the story of the red knight and added the introduction and ending in afterwards," he says. "It wasn't until my publisher said, 'What's he going to try on next? Because obviously he's going to go back,' that I said 'Yes, I suppose he is.'"

By coincidence, both programmes have a shop as their main focus - but crucially, neither establishment is run for financial gain. The costume emporium that Mr Benn frequents is purely a gateway to another world, while Emily's shop in Bagpuss is more of a doll's hospital. Although it didn't come to fruition until years later, McKee recalls the original germ of the idea.

"I was at art school in Plymouth, and I remember going into an antique shop to ask about the price of something," he says. "And as if by magic, a man appeared. I don't know where he came from. But he was absolutely not interested in selling - I never got the price of that item."

For Firmin, the shop used in Bagpuss was much closer to home - it was in fact his own sitting room. Firmin's wife, Joan (who knitted the Clangers), was brought up in a shop and always wanted a shop window in their house. Having six daughters led to the creation of the most recognisable shop window in television history. "We had an extension built when the girls started bringing home boys and it felt a bit crowded," says Firmin. "My wife's brother was an architect, so he designed the extension with a bay window. Eight years later, we made the sets for Bagpuss fit into it."

One of those daughters was to become an integral part of the programme, when sepia-tinged photographs of her bookended each episode. Bagpuss may have been "baggy, and a bit loose at the seams" as the voiceover went, but we all knew that "Emily loved him".

"We wanted it to be a child who owned the shop," says Firmin, "and my youngest daughter Emily was seven at the time and just the right sort of age. So my wife made her a little Edwardian dress and Oliver gave her a bag of sweets for doing it."

Not all of that was based on nostalgia - the stories in both programmes still have the power to captivate, despite the rudimentary filming techniques. For McKee, who wrote Mr Benn as a series of books before it transferred to television, the key was entertaining everyone, not just the children.

"I think I've always worked partly for an adult audience," he says. "The picture book is the one book that is shared - either by a parent and child, or teacher and child - so you can put in things that perhaps only one of those two understands. And sometimes it's the younger one explaining it to the older one, which I've always found fascinating."When Firmin talks about Oliver Postgate, there is pride and poignancy in his voice. The duo shared a long career based on mutual admiration and respect.

"I worked with Oliver from 1958 right through to his death in 2008," says Firmin. "His writing always inspired me, it was so brilliant and I loved bringing it to life with puppets and pictures. He lived within a mile of me in the village, and would come up to our farm to work in the barn, where we made all the films.

"We never had a formal contract that tied us to each other, he would just write a letter and I'd sign it. We had to come to agreements later about merchandise, but it was always a 50/50 split."

Having seen the new stage version of Bagpuss in London, which incorporates three of the original episodes, Firmin and Emily are full of praise for the adaptation.

"When somebody said they wanted to put Bagpuss on the stage, we were really worried," says Firmin. "But I think the result is brilliant." Having guarded Bagpuss closely for years, what would Postgate have made of the show? "He would have loved it," says Firmin categorically.

As for McKee, seeing his bowler-hatted hero brought to life was also a pleasant surprise.

"I had no idea what to expect, and really enjoyed it," he says. "What I also enjoyed was the audience reaction, which was very positive, and the enthusiasm of the Tall Stories group. I like the fact they ask the audience to use its imagination, because if you don't use that, you're wasting something."

• Mr Benn is at the Pleasance Courtyard until 18 August at 11:30am, Bagpuss is at Assembly George Square, until 28 August at noon (10:30am 25-28 August), both as part of the Edinburgh Festival Fringe.