'If the Queen were a flower? She'd be an English Rose, of course!'

He can already be described as a gardener, presenter, broadcaster, novelist and national treasure… and now there is another tag to add to this auspicious list: Royalist. Alan Titchmarsh has penned Elizabeth: Her Life, Our Times, in celebration of the Diamond Jubilee. The colourful tome is part history, part biography, and part open letter of admiration.

Author of more than 40 gardening books, Alan answers immediately when I ask what inspired him to broach this very different feature of the British landscape. ‘I am a great fan, particularly of the Queen,’ he replies. ‘I know one or two members of the Royal Family and I see how hard they work.’

His book moves through the 60 years of Her Majesty’s reign, drawing on her speeches, the impressions of her family and Alan’s own experiences. His cheery voice shines through his words, lending an affectionate note to this portrait of a figurehead. ‘It took me a long time. There was a lot of information to work through and I tried to give it a personal touch as well as being factual,’ he explains. ‘I wanted it to be comprehensive but not rambly.’

It really was a labour of love, and one he took on all by himself. ‘It was all my work,’ he chuckles. ‘There’s an old Northern saying: if you want something done properly, do it yourself.’

Alan first met the Queen in 1985 at the RHS Chelsea Flower Show.

‘I was a bit nervous,’ he confesses. He was asked to show Her Majesty round a garden he’d made: ‘I remember thinking I had better not say too much, and wait until I was spoken to, but I was cajoled into conversation and we had a very jolly chat walking round the garden. She pointed out things that she liked and that she knew. Her gardening knowledge is greater than a lot of people give her credit for.’

He has met her many more times in the years since (her standard reaction on seeing him now, he says, is to say ‘Oh, what are you doing here?’), and his admiration for her only increases. ‘She has an astonishing devotion to duty. It’s quite selfless.’

Alan discovered that her commitment is impressive even to members of her own family.

‘Speaking to her children and asking them what they think about the Queen, the word that crops up more than any other is “consistency”. That doesn’t mean to say that she’s inflexible, rather that she doesn’t waver in her dedication to her role.’

And a demanding role it is. Alan’s book reveals the extraordinary number of engagements and appointments that the Queen still attends (around 400 in the UK and 100 overseas every year), at an age when most people are firmly settled in retirement. From the TV programme All The Queen's Horses

‘The monarchy is in a unique position in that they’ve no reason to climb socially, and they don’t need to get pots and pots of money. All they can do is either lead a life of prolificacy and idleness – as has happened in the past on occasion – or they can work their socks off, which seems to me to be the case at the moment.’

Alan describes how he caught a glimpse of the Queen’s attitude to her role. ‘I sat next to her at a lunch just after the incident with the undercover reporter posing as a footman at Buckingham Palace. We were speaking about it and she said, “I can’t understand the interest. We’re not Hollywood.”’ Alan remembers being rather affected by the remark: ‘I just thought, “Goodness me.” The Queen really is just doing a job. She doesn’t see herself as a film star. Not in the least.’ 

She may not see herself as a celebrity, but there is no denying that the Queen is one of the most famous women in the world – if not the most famous. ‘Her presence is extraordinary,’ states Alan. ‘She has, in a quiet and understated way, enormous charisma.’

This gravitas is part of a public persona that has been six decades in the making.

‘What she’s seen is astonishing. Her first Prime Minister [Winston Churchill] rode in a cavalry charge in the Battle of Omdurman, while her current Prime Minister wasn’t even born when she came to the throne. She’s as sharp as a razor and incredibly strong.’

This Yorkshire chap feels very fortunate to be personally acquainted with the Royal Family, but is adamant that they are just as important to every member of the public: ‘In a way we trace our history through them,’ he muses. ‘And the great body of British folk revere the Royal Family. It’s not mindless adoration, I think people understand that they’re our figureheads, in a way. They add a real colour and specialness to our lives.’

The Queen has unquestioningly given her life to ‘her country, her people and her Commonwealth’, and Alan considers it quite right that the devotion is mutual. ‘You’ve only to go somewhere she visits to see how it buoys people up.’ 

Of course, not everyone shares in his veneration, not least ‘the cynical chattering classes who ghost-write columns in broadsheet newspapers.’ But, unapologetic in his royal praise, Alan has a rejoinder for those, too: ‘I’ve been to media receptions with these sorts of people. What’s funny is that the moment the Queen approaches they go to jelly,’ he chuckles.

‘It’s very, very amusing to watch, because suddenly they vindicate the thing they’ve been criticising by their actions. They realise that they’re in the presence of a remarkable woman.’

He is open in his admiration of Her Majesty, but what does she think of him?

‘I have no idea,’ he laughs. ‘I’ve thoroughly enjoyed her company over the years and I hope she thinks I’m harmless enough.’

Although Alan’s book is not an official biography, he informed the palace that he was writing it and received their best wishes. Does he hope the Queen reads it?

‘Oh, I’m sure she’s sick to the back teeth of reading about herself. But I shall certainly send her a copy – it would be rude not to. If nothing else I hope it can come in useful to help stop a royal table from wobbling.’

As our chat comes to a close, I have one more question for this eminent gardener: if he had to liken the Queen to a flower, what would it be? 

‘That’s easy,’ he says, ‘the English Rose.’

Elizabeth: Her Life, Our Times by Alan Titchmarsh (BBC Books, £18.99).