There are two things you must know about Alan Titchmarsh. The first is that he doesn't take himself too seriously. He tells me he follows Margot Fonteyn's diktat. "To take your job seriously is imperative and to take yourself seriously is disastrous," he says. The second thing is that it is very difficult to find anyone who has a duff thing to say about the nation's favourite gardener.
Before our meeting, I talk to a few people in the industry. "Bless him, love him, wonderful man" is the summary of it, from hard-bitten agents, producers and journalists. This is so rare it's remarkable. While, out in the real world, Titchmarsh's waxwork in Madame Tussaud's has to be wiped down periodically, it's said, because of all the lipstick kiss-marks.
Just about the only criticism you can level at Titchmarsh is that he's ubiquitous. This could be taken as fair comment. What with his gardening programmes, his ITV chat show, his programmes on British nature, his interview with Prince Charles at Highgrove, his promotions in B&Q, his hosting of the Chelsea Flower Show for the BBC, his gardening books and his series of bestselling novels, Titchmarsh seems to bestride British culture like a cheery colossus in a blazer. With a Yorkshire accent.
Now he's turning up on Classic FM, with his own Saturday-morning music show. Is there nowhere that's Titchmarsh-immune? He smiles genially. As you would. "I appreciate it might be a problem for some people. So, just turn me off. I don't mind." A pause. We are sitting in the main studio at Classic FM. This is probably not a politic thing for him to say. "Well, I do mind, but you can."
Apparently it's only a few nasty journalists who write horrid things, such as "Alan Titchmarsh is EVERYWHERE, and that is a pain". "The public are quite good," he says. "I stuck my head over the parapet and started writing novels in 1998. I wrote the eighth one last month. They have all got into the Sunday Times top ten, so that's all right. I'm not bothered about whether they're well reviewed. People like reading them."
You see? Knock the Titch all you like, but the proof is in the charts and the viewing figures. Even when he suffers a bit of a blow, such as the cancellation of his Radio 2 Sunday-night show, Melodies for You, after four-and-a-half years, he just keeps on being Alan Titchmarsh.
And before you know it, there's the controller of Classic FM booking him for a rather similar-sounding programme, only in a slot that's twice as long. "I was told Melodies for You wasn't being recommissioned, and I said, 'That's a shame', because it had a great following. It was a shame, but hey! I'm happy to redress the balance on Classic FM."
Is he a classical music nut? He admits he's not a fanatic such as fellow Classic FM signing John Suchet, but he started listening to classical music when he was a boy.
"My dad had a Fidelity record player. It was very posh because you could put the lid down while playing LPs, which in the 50s was really something. I remember he bought the Ace of Clubs recording of Fingal's Cave, and Mario Lanza albums. He got me into it."
Titchmarsh particularly loves Baroque music, especially Handel, along with the "light" classics, operetta and musicals. He was a choirboy and loves singing. Rather Titchmarshly, he met the future Mrs Titchmarsh in the local operatic society, during a production of Half a Sixpence. "I played Buggins, the pessimist," he smiles. "Casting for type!"
That's why people love him, of course, because he is so much the opposite. There is simply no cynicism going on with Alan Fred Titchmarsh, 62, born and bred in Ilkley, West Yorkshire, who left school at 15 to be an apprentice gardener with Ilkley council. His enthusiasm is infectious, which is what makes him such a winning broadcaster. He gets excited about Offenbach, planting bulbs or seeing a cabbage grow - so much so that you want to grow one, too.
He clearly works like a dynamo, getting up at 6.30am and knocking out several thousand words of fiction before lunch. But after that, writing various columns and answering his postbag (which is clearly gargantuan, and may or may not contain items of underwear sent by ardent fans), he will potter around his four-acre Hampshire garden. This is what really turns him on.
Gardening has been his life and, in his view, it is life. Is it more important than, say, Newsnight?
"Much more important. Tomorrow, Newsnight will have different stories and priorities. Gardening is more important than politics. It has a consistent point of view. And that is: that a piece of ground should be cherished. If you live in the countryside and look out of the window, you will see there is no ostensible difference between this year and 200 years ago. The natural world has a kind of stability. There is a cycle that's reliable and sound, and that is real life to me. There is a greater world out there that people can't see because they're glued to a screen. Gardening is the stuff of life. It's about putting a seed in the ground and making it grow."
That is Titchmarsh's other great skill. He makes it sound so simple, whether the issue is Strauss, hedging, or if having pampas grass means you're a swinger. "I've never liked it! I've never needed it!" Ooh, Alan, you are a tease.
His favourite month is May. "I was born on 2 May [ladies, take note] and there is some- thing so lovely when your birthday is linked to a time that you love. It is such a lovely month, with the blossom unsullied by the summer breezes. It makes you want to be an optimist, even if you're not. And that is the most important thing. What does it matter, what critics say? If I have managed to get one or two people to plant some daffodils, or a tree, and the blosssom has come out, they'll be looking at it now. And that is the message."
Is that his mission? It is. "Gardening is my passion and my mission. Music is my great solace. The chat show, which is conversation, is everyday life. And if my annoying little smiling face at B&Q encourages people to have a go at DIY, then why not?"
You see? There is simply no way around the phenomenon that is Alan Titchmarsh. You just have to join in with everyone else, and become a fan.
Alan Titchmarsh presents on Classic FM, Saturdays from 9am
This is an edited version of an article in the issue of Radio Times published 3 January 2012