There are five words that define Gyles Brandreth’s life, and another four that are the most important ones in the English language, he declares.

“The five words that have driven my life are ‘busy people are happy people’, and the four words that rule my life are ‘listen to your wife’,” explains Brandreth, 73. “And the truth is, on the few occasions when I haven’t listened to my wife, it’s all gone wrong, so basically I know that’s the right philosophy. My wife keeps me grounded.”

After nearly 50 years of marriage, that’s a ringing endorsement for the broadcaster’s wife Michele Brown – with whom he shares three children, seven grandchildren, and a fair few teddy bears. The natty line in jumpers he’s renowned for though, and stacks of clutter he’s amassed through his six-plus decades of busyness are his, and his alone.

“I’m a great hoarder, which my wife doesn’t like,” Brandreth admits. “She’s told me that when I die, the first person she’s going to call, before she calls the undertaker, is someone from the local skip company, so they can collect all my rubbish. All my jumpers, all my diaries – I’ve kept everything and it’s all going off to the skip – although I’m hoping it won’t be for a while.”

Fortunately, the affable former MP – who’s childhood memoir, Odd Boy Out, has just been published – leads an admirably healthy life, and he says he feels incredibly lucky about the state of his health and wellbeing.

“Touch wood, I’ve been very lucky with my wellbeing and my health, and probably taken it too much for granted. I’ve been busy, and I’m not really given to much introspection – I probably reflect my generation with that,” he shares.

“When it comes to wellbeing, my philosophy is moderation in all things. I’m lucky – I don’t drink, I don’t smoke, if I want to lose weight I do a low-carb diet for a while. I probably should take more exercise than I do, but I do keep walking and try to do my 10,000 steps, and I keep busy, and busy people are happy people.”

And he must be very happy, because he’s very busy. As well as frequently popping up on the radio, TV gameshows and other series, such as The One Show and Celebrity Gogglebox, Brandreth is touring with his rescheduled one-man show, Break A Leg!

He has also written numerous books, also including the recently-published Philip: The Final Portrait about his friend Prince Philip, is the very proud owner of a vast collection of teddy bears at Newby Hall in Yorkshire, and even finds time to co-host the podcast Something Rhymes With Purple, with his friend and Countdown colleague Susie Dent. Oh, and perhaps most surprisingly of all, he’s just started a new knitwear fashion label.

“Actually, what is lovely about life, is that it’s full of surprises,” Brandreth muses. “When I was a little boy, I used to live in Marylebone in London, near streets where there were fashion wholesalers. And I remember going past them, looking at these beautiful clothes and seeing names like Christian Dior, London & Paris, and I thought that one day I was going to have a fashion label.

“Now, here I am in my 70s, and I’ve just got my own fashion label – Gyles & George, London & New York – for my jumpers. Can you imagine that, isn’t it exciting? That’s rather wonderful.”

So, at the age of 73, does this broadcaster, novelist, former politician, comedian, raconteur, teddy bear collector, fashion icon and all-round bundle of enthusiasm and energy, have any plans to slow down?

“I did promise my wife about 50 years ago that we wouldn’t work every Sunday, and I still keep promising every year that that’s going to happen,” he admits with a chuckle. “What I do, you couldn’t really call it work – when you appear on television gameshows, you’re just playing a game, and collecting teddy bears is hardly work. Writing books is work, I suppose – you have to be there every day. But the things I do are fun things.”

He’s kept a diary since he was a little boy, and when writing Odd Boy Out – so named because his publishers insisted he was “an oddity”, a statement Brandreth doesn’t dispute – he discovered an entry which revealed the origins of one of his core philosophies. It was something his headmaster had told him when he was nine or 10. “He said: ‘Brandreth, busy people are happy people – remember that.’ And I think from that age, I’ve always remembered it, and I think I’ve had a happy life because I’ve been busy all the time.

“Sometimes people ask me why I keep working at my age, and I say I need the money – and it’s true, I do need the money, we’ve got three children and seven grandchildren, and we discovered over the years that money is the one thing keeping us in touch with them. But I also work because I like to be busy.

“I do lots of different things, and when one door closes, another one opens,” he adds. “Noel Coward once said: ‘Be like a rabbit, keep coming out of a different hole’ – so I’ve got lots of different holes to come out of.”

And, as he happily sits in a coffee shop sporting one of his trademark jumpers with a big red heart on the front, Brandreth concludes: “To be honest, I’m just very happy to have survived and be here, still to be gainfully employed, still wearing my jumpers, still popping up. I’ve got no complaints.”

Odd Boy Out by Gyles Brandreth is published by Penguin Michael Joseph, priced £20. Available now.