If I felt inclined, and I don’t because I don’t want to be robbed every night and stabbed over the breakfast table every morning, I think I’d make a rather good foster parent.

Unfortunately, despite my fondness for reading Winnie-the-Pooh stories and having big coal fires to keep everyone warm at night, I would not be deemed suitable, because various well-meaning councils have determined that it’s bad to place a child in the care of someone who is fat and who smokes. Sorry then, Lee. No Pooh and tickets to Top Gear for you, my lad.

This spotlights an interesting new development: that the government we elect to build street lamps and erect park benches now has a view on what makes a good parent and what makes a bad one. Fat’s bad. Smoke’s bad. Predatory vegetablism, though, is fine. And so is keeping the house at -42C for environmental reasons.

Certainly, any parent who turns up to watch their kid play in a school sports match would be deemed “extremely good”, even though I’ve just returned from watching my son play rugby and it seems that absolutely no dad in Britain can do this properly.

I do not know what it is that causes normal, bright and funny people to lose their grip on reality as soon as they find themselves standing alongside a school sports pitch. But since everyone does, what I’ve done for you is to prepare a handy cut-out-’n’-keep guide to what’s acceptable and what’s not.

First, parents must remember that they are an embarrassment to their children. Mick Jagger is an embarrassment to his kids. I am an embarrassment to mine. You are an embarrassment to yours. Everything you do. Everything you say. Everything you wear. It’s all completely wrong. So here’s a tip when on the touchline. Be normal.

If your child’s team scores a try, you may applaud but do not - and this is something I witnessed just two hours ago - run onto the pitch, bellowing like a wounded animal, with a red face, a jugular vein standing 6in proud of your neck and your arms held aloft like a triumphant boxer.

Because after you have reached the middle of the pitch and sunk to your knees in a puddle of gratitude and happiness, you will realise you are the financial director of a leading advertising agency and you have just made yourself look like an idiot.

Massive demonstrations of pride are acceptable if you are a Chelsea supporter and Didier Drogba has just slotted his eighth of the afternoon past Liverpool. But when you are watching a bunch of muddy 12-year-olds running about like starlings, they are not.

Also, no matter how knowledgeable you might be about the sport you’re watching, do not feel free at any point to offer loud and hectoring advice. This will make everyone on the team want to kick you in the head and, since it’s against school rules to attack visiting fathers, they will simply wait until they are in the showers after the game and kick your child instead.

You may not smoke around your children to protect their lungs. You may feed them only brown rice to keep the cancer away. And you may give them only warm and fuzzy video games to preserve their minds. But if you shout on the touchlines you will end up breaking their noses by proxy. I guarantee it.

Furthermore, offering helpful hints at the top of your voice will irritate the ref, who may at some point come over and ask you to be quiet. This - and I’ve seen it happen twice - can end in a fight. And no one wants to see the divisional manager for a supermarket chain rolling around in the mud trying to punch his son’s history teacher in the face.

You can always tell when people are likely to behave like this because they will be supporting the other team and will have taken a day off work and driven hundreds of miles to be there. This means the person in question is extremely enthusiastic – and that means he will suddenly lose track of what you are saying to him and start jumping up and down shouting “Man on” and “Face the ball” and other unintelligible things. And the next thing you know, he’ll be wrestling in an undignified middle-aged way with Mr Jenkins from IVb.

If you find that someone has come from far away, walk off and talk to one of the women who turn up without a spouse in tow because they will be grateful for the company. I know this because any man who puts “supporting my son in rugby matches” below the line of things he’s prepared to do in the way of parenting is plainly hopeless as a husband. And therefore his wife will want to have an affair with you. This is why almost all women on the touchline at rugby matches are dressed up to the nines.

However, and this is critical, when you have become engaged in small talk with a pretty mother and you are arranging to meet for tea afterwards, do not get so distracted that you miss your child scoringa try. He doesn’t want you there. He doesn’t want you to make a noise. But trust me on this: he wants you to be watching at his moment of glory. So pay attention.

Now for the tricky part. When it’s your own child who’s put the team in front, for Christ’s sake, keep calm. Do not shout, “That’s his 18th of the season so far”, because everyone will hate you. What I do is claim that it’s his first-ever try and then, to hammer the point home, pretend to faint. One day I’m hoping this will make the pretty mother I’m invariably talking to give me the kiss of life.

Of course, this might irritate your boy if he were to turn round and find his dad being snogged by Fortescue minor’s mum. But since just standing there will annoy him anyway, you may as well give it a try.

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