Like so many men, I’ve made a terrible job of looking after my skin. Born in 1963, I grew up at a time when every pasty white Briton wanted to be tanned, and the darker the better. It suggested you’d been abroad, when travel was expensive and therefore glamorous. Sure, you could buy Coppertone or Ambre Solaire – but it didn’t offer much protection even if you used it. The term SPF, or sun protection factor, was introduced in 1974, but I don’t think I heard it for another 10 years, by which time I had been burned more times than you could count.

And that set the pattern for most of my life. However fierce the sun, slapping on sunscreen, or even wearing a baseball cap, felt like too much of a faff, or too late, or both. I’ve grown a little more sensible since I met a woman who takes care of her own skin and that of her kids. But even now, I use about a tenth as much as sunscreen as they do.

And that would be fine, if all I was risking was a few wrinkles. But hundreds of thousands of Britons are diagnosed with skin cancer every year, mostly because they got too much sun. “A history of sunburn increases your risk of skin cancer,” Cancer Research UK reminds us. “The risk is especially high if you were sunburnt several times during your childhood.”

So now, at the age of 61, I find myself standing in front of the mirror and interrogating my increasingly mottled face. “How could I have been such an idiot?” I ask myself. And, more importantly: “Have I got away with it?”

In the hope of answering that last question, I’ve come to Salford Royal hospital’s dermatopharmacology unit, where I have a date with a Visia skin-analysis machine. This expensive bit of kit will take high-resolution photos of my face, using a combination of visible and ultraviolet light to reveal everything from redness and brown spots to wrinkles and crow’s feet. As Dr Abigail Langton, senior lecturer in skin ageing at the University of Manchester, explains before talking me through the results, these don’t indicate cancer by themselves, but they do give some insight into how well or badly I’ve looked after myself.

So I sit down, stick my chin into a little cup and and close my eyes while a light flashes three times. Then it’s over to the screen to see how I measure up.

The first signs are not encouraging. “You’re worse than average for wrinkles,” Langton tells me, after the computer has compared me with a database of other men of a similar age and skin colour. Not all of my wrinkles are obvious to the naked eye – but that’s rather the point of the Visia. It’s popular in aesthetic medicine, to show clients how their skin is changing even if they don’t realise it, or to simulate the effect of various treatments.

Just how wrinkly am I? Well, Langton says, all of today’s results are percentages; anything above 50% is better than average, and anything below it is worse. And I’m on … 15%.

I console myself with the thought that maybe it’s not all down to the sun. “Some of the wrinkles we see might be due to muscular activity,” says Dr Tamara Griffiths, a consultant dermatologist and president of the British Association of Dermatologists (BAD). If “muscular activity” includes squinting and frowning, that might explain at least some of my score: I’m very shortsighted, I keep forgetting my sunglasses and I’ve always got the hump about something.

Texture – “the lumps and bumps on your face” – is much better, at 56%. Langton says I have a “quite smooth, clear complexion”.

As for underlying skin damage, as revealed by the UV light – “zits, freckles, brown pigmentation, anything like that” – I’m again a little better than average, at 58%. “Brown spots” are better still at 69%.

But then we’re back to the bad news. “This is an interesting one,” says Langton. That’s “interesting” in the same way that your GP might call an abnormal blood test “interesting”. “We’re looking for redness in the skin, and you can see it here in your forehead, your nose, your cheeks … You’ve got quite a tanned complexion, but your underlying complexion is a lot redder than average.” That’s putting it mildly: I score just 2%, meaning I’m more lobster-like than 98% of irritable white sixtysomething men.

This doesn’t necessarily mean I’m more weather-beaten than them, more that this is how the weather-beating expresses itself. “You’re the type of person that probably manifests sun damage and skin ageing with blood vessels,” Griffiths says.

More surprisingly, when I go back to the Visia for some side views, we discover that there’s more sun damage on the right of my face than on the left – more wrinkles, more brown spots, more crow’s feet. Do I drive a lot, Langton and Griffiths ask. (There’s a famous photograph of an American truck driver that shows one side of his face – the one nearest the window – with innumerably more wrinkles than the other.) No, I tell them. I barely drive at all. All we can come up with is that maybe it’s down to the Guardian’s offices, where I sit next to floor-to-ceiling windows. Perhaps I should pull down the blinds, but then I’d miss the glorious views of the Regent’s Canal.

The overall verdict? “The condition of your skin is almost exactly as expected for someone of your sex, age and skin colour,” Langton tells me. That’s probably better than I deserve, given that I spent most of my 40s in the open air, hiking, gardening, barbecuing and skiing without either a hat or any kind of sunscreen. But it doesn’t tell me what I most want to know: do I have any signs of skin cancer? What should I be looking out for?

The most serious form of skin cancer, melanoma, usually starts with a new mole, or a mole that has changed in size, shape or colour. Griffiths has a handy mnemonic for what to look out for. “A is asymmetrical: it’s not a mirror image of itself. B is border: the border is notched or jagged rather than smooth. C is colour: we like a dark brown as long as it’s even in colour, but not if it’s got pink or pinky brown and the like – if it’s blotchy in colour. D is diameter: we don’t like it if it’s greater than 6mm or so. If it’s big and it’s also blotchy with irregular borders, that’s higher risk. And then E is evolving – it’s rapidly changing or you definitely didn’t have it before.” You should also worry about the “ugly ducklings”, she says. “If you’ve got a lot of moles, but one just looks very, very different, then you should have it checked.”

“It’s very difficult,” she says, “because melanoma can be easily missed. Even dermatologists, sometimes we look at them all and if we’re in doubt about something, we cut it off.”

Non-melanoma skin cancers are much more common and generally less dangerous. But, Griffiths says, they’re “usually quite insidious”. The most common type, basal cell cancers (BCCs), “can vary greatly in their appearance”, according to BAD, “but people often first become aware of them as a scab that bleeds and does not heal completely, or a new red or pearly lump on the skin. Some BCCs are superficial and look like a scaly red flat mark on the skin. Others form a lump and have a pearl-like rim surrounding a central crater, and there may be small red blood vessels present across the surface. Most BCCs are painless, although sometimes they can be itchy or bleed if caught.”

Sometimes BCCs occur on the backs of your ears, Griffiths says, and you only notice them because of blood on your pillow.

Squamous cell cancers (SCCs), meanwhile, are “like a warty type of lesion”. As BAD puts it, “most SCCs usually look scaly or crusty, raised and rough as they originate from the outer layer of the skin. Underneath the scale, there may be an ulcer that bleeds easily … SCCs can occur on any part of the skin, but they are more common on sun-exposed sites such as the head, ears, lip, neck and back of the hands.”

“Do you want me to check your skin?” Griffiths asks me. Of course I do. So, as requested, I “pop my top off”.

The first thing to catch her eye is a red mark on my right forearm. “I think that’s recent,” I tell her. “It might be where the dog’s claw caught me.” Bloody Stevie, I think: always jumping all over me the minute I come in the house. “It looks like a little bruisey-type trauma,” Griffiths agrees.

“You actually have very few moles,” she says, as she examines my chest, shoulders and back. Then she asks me to tilt my head so she can see the top of it. “Sometimes men who are thin on top think they’ve got really dry skin,” she had said earlier. “It’s not dry – it’s actually sun-damaged – but it presents with crusting or scaling or flaking.”

“You have a few little tiny rough bits on top of your scalp,” she tells me now, “as well as a few benign-type moles and a couple of slightly dilated oil glands on your forehead. But I don’t see anything to cause concern.”

What about this red and brown blotch under my left eye? I only noticed it a year or two ago. It’s just a little blood blister, she reassures me, with a freckle next to it. You can see it on the Visia images. “What happens is that some of the superficial blood vessels dilate and then don’t close again.”

The examination takes just a few minutes, and would probably have been quicker if I hadn’t asked so many questions. How do I feel about what she’s told me, Griffiths asks. I feel good, of course. It looks like I’ve got away with it.

But we both know this doesn’t mean I always will. “Sun damage is cumulative,” Griffiths points out. “I tell patients it’s like a glass being filled with drops of water. Once the glass starts overflowing, you can’t really drain it. You don’t need those drops going in.”

So how do you keep the glass from filling? The simplest thing, of course, is to stay out of the sun when it’s at its hottest. In the UK that’s between 11am and 3pm, from March to October, according to the NHS. I could also cover up, with a hat, sunglasses and a long-sleeved top. But the hardest thing will be using sunscreen. It’s easy to forget that you can burn even on a cloudy day, or outside of spring and summer. BAD recommends we slap on sunscreen of at least SPF30 whenever the UV index – which you’ll find in the more detailed weather reports – is three (AKA medium) or higher.

“A lot of it is about forming a habit,” says Paula Geanau, also of BAD. “Our advice is to put sunscreen on about 15 to 20 minutes before you leave the house – and then, 15 to 20 minutes after you’ve left it, to put on another layer. That way the first layer will have had time to dry and create a protective barrier, and hopefully the second layer will cover the areas that you may have missed the first time.”

And don’t put too much faith in products that claim to last all day: “After you rub it on your skin, you could easily rub it off or sweat it off or wash it off. If you go to the beach and get in the water, it’s gone. People shouldn’t get a sense of overconfidence.” The NHS’s advice is to reapply sunscreen at least every two hours.

“The other take-home message is that people definitely don’t use enough sunscreen,” Griffiths says. “You need to use a tablespoon-size amount for the head and neck and reapply it a few times a day. My advice to patients is: buy something that you like and that is not too expensive. If it makes your skin white and you don’t like it, you won’t use it. If it’s too expensive, you won’t use it enough.”

I’ll try to remember all of this. I expect I’ll fail more often than not. But having apparently dodged a bullet, I’m going to at least attempt to stay out of the firing line.