It usually feels quite good when someone wants to borrow your clothes: when you catch your girlfriend wearing one of your old sweaters, for example, or your best mate asks to borrow a dinner jacket for a party. It’s less comforting when your teenage son tries to cadge an item from your wardrobe — not only because it will be returned, weeks later, smelling of sweat, stained with ketchup and suffering from skateboard tears, but also because if a 15-year-old covets something you wear, then either he, or you, is doing something very, very wrong indeed.

The troubling period that is middle youth has a lot to answer for, but it is mostly responsible for hordes of men — many of whom are fathers — spending their weekends dressed in the standard kidult uniform of low-slung baggy jeans teamed with hoodies and trainers. The problem is that it’s just not appropriate: you haven’t returned from a session at the skate park; neither are you going to a Tinchy Stryder gig that night.

It’s a common mistake made by so many Peter Pan men — Rhys Ifans, Mick Jagger or Ronnie Wood, for example. So why dress like this? It’s high time the hip-pop brigade pulled their socks up — or, at least, put some on.

It’s a nightmare for teenagers, but it’s also a nightmare for us. As more “youth” trends get appropriated by wrinklies, the younger generation have little option but to colonise other, more extreme looks. This can be the only explanation for the rise of the emo. Whoever thought the goth look would sneakily return in a slightly revamped form? This trend mustn’t be encouraged: reluctantly accompanying my 12-year-old son to a My Chemical Romance concert a few months ago, a goth girl’s cobweb top accidentally got caught on the button of my Prada jacket. It was dark, and it took a good few minutes for us to disentangle ourselves. My son looked on in disbelief, thinking I was on the pull. Even if I was, I’d like to think my chat-up methods are more polished than attaching myself physically to someone “by mistake”.

Dressing appropriately for your age is no mean feat since the rules and boundaries became so blurred. We no longer arrive at key stages in our lives at the same time: you are just as likely to be a new dad at 42 as at 26; you could be the CEO of an internet empire at 23 or swap a job in the City to go bumming around India for a year at 38.

Role models are few and far between, too. There is no way we would dress as our fathers did at our age (with the exception of honking sloanes, of course, who dress like their parents as soon as they are out of nappies). And, at the other extreme, most of us would, I hope, feel a little uncomfortable dressing like the aforementioned ageing rockers, or like the chronically age-phobic Madonna and Michael Jackson do at 50. I say most, because at Madge’s Wembley gig a few weeks ago, there was an alarming number of middle-aged women — and a few men — dressed like the singer.

Movie stars tend not to be too helpful, either. The days of style icons such as Cary Grant and Steve McQueen are long gone. It's all beanies, combats and V-neck T-shirts today. Everyone looks as if they have just come off the set of a Judd Apatow movie. So to whom do you turn for guidance? Happily, there are a few real men out there — George Clooney, Hugh Grant, Guy Ritchie and Jose Mourinho, for example — who manage to look modern, masculine and age-appropriate off duty. These guys tend to rely on a few well-chosen staples (see right), so what you notice about them first isn’t their clothes, but the fact that they simply look good. They appear ageless and are living proof that there’s a middle ground somewhere between Russell Brand and Gordon Brown.

Ultimately, the easiest way to avoid the kidult conundrum is this: if one of your children compliments you on something you’re wearing, get rid of it. Sometimes it’s tough: I’ve had to say a sad goodbye to a charming pair of coloured Uniqlo jeans, a navy Gap pea coat and a very expensive pair of Pierre Hardy high-tops. This selfless sacrifice has, so far, paid off. Despite living worryingly close to Camden market, neither of my children has, as yet, shown any signs of impending gothdom. 1

JACKET

Richard James does a neat-fitting navy blazer and Kilgour has a great unstructured grey flannel jacket. Check out Reiss or Cos for less expensive alternatives.

SHOES

Avoid trainers, especially high-tops (fun, but too young). I suggest heavy-looking shoes this autumn, such as a brown Waterline pair by Church’s. Otherwise, invest in penny loafers (Tod’s are good) or brown suede Chelsea boots. If you want something more casual, opt for navy or grey Sebago deck shoes.

SWEATERS

This autumn, the best-value knitwear is at Uniqlo. Its merino wool collection has great-fitting V-necks, turtlenecks and polo necks. Go for navy, brown, moss green or, if you’re feeling brave, baby pink. If you want a pattern, look at the stripy sweaters in Gap or, for a little more luxury, try Pringle’s cable-knits.

CARDIGANS

These are still in fashion and can look great, if worn properly. For a preppy look, team with a shirt and tie: a look that works for any age, from eight to 80. However, avoid cardigans if you have a paunch: they will only exaggerate it. Marks & Spencer have a cashmere cardigan for £149.

SHIRTS

Don’t wear too formal a shirt at the weekend. Go for a soft collar and a loose shape: pale blue is a safe bet. Check shirts are back, but be careful not to look like an extra from Brokeback Mountain — Margaret Howell and Aubin & Wills do good versions.

CHINOS

Much easier to get right than jeans. Don’t go too baggy, or you will look like a sack of potatoes. I recommend stone-coloured chinos by Acne, cotton chinos from CP Company or a pair of Hackett’s moleskin trousers.