I was more into the gadgetry, the hi-tech, more scientific stuff.”He was clearly devoted to his late father and remains so today. He recalls how he would visit Jim Henson at his studio every weekend and hang out in the workshops where they built the puppets “I had an enormous amount of respect for him He took it all very seriously. It was important for him – so it was awesome for me.” But he still rebelled “really badly” at 15. “I was in boarding school and suddenly it all became too much for me I didn’t want to use my last name I was studying astrophysics and wanted to be a physicist. I’d get straight As in art and film, but all I cared about was physics This lasted until I was 18. While I was transferring from one university to another, I got a holiday job at my father’s company, building special-FX puppets, and then it really excited me all over again I decided there and then I wanted to be a movie director.

So I’m still doing that holiday job.”His father welcomed back the prodigal son, took him under his wing and set him up in other people’s films, “to see how it worked out in the real world”. Between 19 and 23, he did character special effects around the world, in Return to Oz, Santa Claus – The Movie, and Little Shop of Horrors, all independent of his father. Fully apprenticed, he moved back to the Henson family firm and stayed there as director. It’s Mr Henson Jnr whom we have to thank for Kermit dancing down the street (on visible frog’s legs) with Robin on his shoulder in The Muppet Christmas Carol.”Of all his creations, my father most resembled Kermit,” says Brian “They’re virtually inseparable.

In fact, he started doing Kermit when he was only 21, long before the show. It was before he’d learnt the arts of performance, and Kermit was kind of an awkward character in the first few years As my father became more sophisticated, so did Kermit. And they both became this personality, with a very clear morality and philosophy of life but with a very naughty sense of humour underneath. My father loved nothing better than a really good, well-conceived practical joke”.One’s heart sinks at the prospect. But Brian tells a droll story about Duncan Kenworthy, when he was head of production for the Jim Henson Company in the UK. “He was always pushing my father, saying, ‘Jim, we need to do more adult stuff.’ So one day they set up hidden cameras and hired a lovely actress to pretend to be a producer, to come in and pitch the idea to Duncan for an adult version of Animal Farm.

She’d say, of course, ‘This is a very political piece of literature, but I’m thinking of a more adult version, where we put a child into it, and the child and the animals would love each other, and I mean actually love each other, it could get quite graphic…’ And then my father comes in, and Duncan’s giving him signals that this person’s a lunatic, and of course my father starts agreeing with everything she’s saying. They filmed it all and threw a party for the screening.”He laughs Brian Henson laughs a lot. He sounds like a man with a charmed life – growing up in Muppet heaven, heir to a family fortune, later carving out his own niche as a film director at the cutting edge of special-effects technology. He talks with immense pride about the 560 special “visual effects” to be seen in Jim Henson’s Jack and the Beanstalk: The Real Story. “We created a complete world for the giant world, and wanted to make everything look real, not like a story-book version.