TRINNY WOODALL, the fashion stylist and television presenter, was quite open the other day about her love of Botox. “I’m still having Botox – I started at 35 – and I love it,” the 53-year-old told a magazine. “I’m not ashamed of wanting to look my best and of wanting other women, of any age but particularly of my age, to look as good as they can.”

Many household names have had Botox injections. Actress Olivia Colman says she loved it. Music mogul Simon Cowell once admitted to having had “too much” Botox. Singer Danni Minogue has said she used Botox during traumatic times in her life.

On the other hand, many celebrities are sceptical of the process, or prefer to age naturally. Actress Jennifer Aniston once tried Botox but disliked how it made her face feel: “I think [Botox] makes women look older. Harder.

The warmth in their face goes away... People lose perspective. That’s what stopped me. I thought, ‘Let’s not even get on this train; it’s a ride you can’t get off’.” The actress Susan Penhaligon has ruefully spoken of a foray in Botox that left her “looking like a character from Planet Of The Apes”.

Regardless of the pros and cons, increasing numbers of ordinary people are turning to Botox and other non-surgical treatments to hold back the years. The British Association of Aesthetic Plastic Surgeons said earlier this month surgical procedures declined by nearly eight per cent last year, “now that there are so many less invasive enhancement options to explore.” The association also pointed to one intriguing statistic: millennials are expected to take as many as 25,000 selfies in their lifetime and more than half of women admit to enhancing every photo they ever post.

Many of them are increasingly opting for non-surgical options, such as Botox and fillers. A January 2017 study by the American Society For Aesthetic Plastic Surgery found the number of US women aged between 19 and 34 who were undergoing the Botox procedure had risen by 41 per cent since 2011.

One Glaswegian specialist in “facial aesthetics” is Dr Darren McKeown, who speaks knowledgeably about the positive impacts his work can have and is, he adds, Scotland’s biggest buyer of Botox. Now 36, he has been intrigued by cosmetic practice since childhood.

“I became fascinated by the concept you could alter your appearance, and there was what I perceived to be value in that,” he says. “It was a combination of reading books and what was in the media at that time. Michael Jackson and Elizabeth Taylor were making headlines, and not necessarily for the right reasons, but I found the whole concept interesting.” He remembers reading a book about life in Los Angeles, “where plastic surgery was big business.”

The interest pursued him through medical school. After graduating he worked for the NHS and became a member of the Royal College Of Surgeons, but he was already being lured in the direction of non-surgical and less invasive procedures. As a medical student on a summer elective term with a Beverly Hills plastic surgeon, he saw the impact a new drug, Botox, was making in America, and he had never forgotten it. He left the NHS and set up on his own, in Glasgow, in 2007. He has been full-time for the last seven years, and he also has a practice in Harley Street, London.

“One of the key points is that our understanding of the ageing process has become much more advanced,” he says. “Before, doctors and surgeons assumed you aged because gravity pulled your tissues down. But as our understanding of anatomy became more sophisticated we realised gravity probably plays a relatively small part; it’s more to do with atrophy of the facial skeleton, so there’s less tissue supporting the skin, and that’s why the skin begins to take on the appearance of sagging. There began a shift away from pulling things really tight to restoring volume in the face. That’s when the opportunities for non-surgical treatment began to flourish.”

Patients come to his clinic in their thirties, and he says he tries “to keep them looking roughly that way until their fifties. But there comes a point in the ageing process where the tools we have are imperfect, and we can’t cure everything. Recognising that limitation, when to stop, is one of the key features of my practice.”

Non-surgical treatment can have a interventionist aspect at the outset of the ageing process in order to try to prevent decline, he adds. “But some people take it to an extreme and advocate doing Botox at 21. I’ve even seen people talk about doing it at 18 to stop them from ever developing wrinkles.” But this, he believes, is not psychologically healthy; long-term, it’s not healthy for the face, either. He had Botox in his late teens, a decision he regrets now. “At that age you’re not fully developed, you don’t know who you are or what you want to be. A lot of young people make impulsive decisions that they later regret.

“When I like to begin intervention is when I can start to see lines and wrinkles on the face at rest, not just when your face is moving. That’s a good time to start thinking, ‘Okay, let’s do something small to keep on top of it before it develops into a big problem’. And for most people that would be at some point in their thirties when that happens.”

As another Botox doctor, Dr Tracy Mountford, put it in The Times recently: “I’m not encouraging everyone to have lots of Botox or fillers, but light touches from your late thirties will prevent ageing and hold you in a state of aesthetic suspended animation so at 40, 45 and 50 you will still look like you did 10 years previously.”

Ten per cent of Dr McKeown’s clients are male. They range from image-conscious younger men to middle-aged business worried about younger competition stalking them in the workplace. Others are fathers of the bride, who want to look their best on the big day.

The biggest difference between his Glasgow and London practices is there are more sun-damage cases up here. “We do have a long history of sunbed use and holidays in the sun. When Glaswegians go on holiday they tend to want a tan they can show off when they come back. Women, however, are starting to recognise the importance of protecting their skin from the sun.” Some people still use cooking oil on their face to deepen their tan.

He also acknowledges some young people who have posted selfies showing their youthful beauty on Instagram are seemingly disconcerted by them a year later. “People spend ages taking the perfect image from different angles and will put a filter through it then post it. A year later they’ll look at it and think, God, how amazing I looked last year’ and they’ll tell me they’re worried they don’t like that any more. But I tell them they’ve forgotten they never actually looked like that: it was a carefully manipulated image, a snapshot in time. And that can be quite dangerous.”

Was Jennifer Aniston raising a valid point when she said Botox can make women look older and that their faces lose their warmth? “I think so. You see that especially on a lot of young girls on reality programmes such as The Only Way Is Essex. I think a lot them look older than their years. If you have the same standardised approach to everybody who comes through the door, yes, you will lose some of the natural character [of their faces]. But that’s not the way it should be. High-quality work should be minimal, and tailored to the person, and it should enhance what they’ve got, rather than change the way they are.”

Botox treatments aren’t cheap.

Dr McKeown charges £325 for a standard-dose upper face treatment and £425 for upper and lower face treatment. But if you believe such work will take years off your appearance – if you side with Trinny Woodall and want to look your best at an age when things are starting to drift south, it’s money well spent.

Most of Dr McKeown’s customers come once or twice a year, some three or four times. “Any more than that is unhealthy. But the people who fall into that category are probably a much smaller proportion than what you would expect it to be. The media representation of the aesthetic practice is it’s all crazy women who all look really weird and they’re chasing something they’re never going to achieve. That’s actually not the reality of what we see.

“Most women and men [who come here] are very normal and well-balanced, going about their average, everyday job. If you were to see them in the street you would never think for a minute they’re the type of people who would get these treatments, because they don’t look like some of the women you see in the newspapers or in the media. After all, the thing we notice most are the most extreme examples. But those are outliers, and that’s not what it’s supposed to look like. When this is done, people should look just like themselves.

“I like that I make people happy,” he says finally. “In most aspects of medicine, you’re dealing with breaking bad news on a relatively regular basis. Whereas here, I take someone who’s normal, and make them happy. Nine times out of 10, people walk out with a big smile on their face, and they come back for follow-up appointments and they’re bounding with confidence. There’s a lot of job satisfaction in that.”