I’ve just read a teens’ guide to good manners.

While it is all very useful — be punctual, don’t leave mobile phones on the table at mealtimes, look waiters in the eye, and say thank you, don’t talk about yourself all the time, don’t be a nasty person — I personally think such tips would be more usefully directed at adults.

I have two teenagers, and I meet a lot of their friends. While not perfect — particularly towards us parents — they are mostly polite and considerate.

Adults, on the other hand, are mostly not. I come across rude people on a daily basis. Barging and pushing, shouting, glaring, dropping litter, When I’m on the bus or train, it is usually an adult speaking loudly into a mobile phone.

Last week I sat half a carriage away from a man involved in a dispute with a holiday insurance firm. By the time I’d travelled from Bradford to Leeds I knew his medical history from birth, home address and bank account number.

I’m often in shops, standing behind people having conversations on their mobile phones or texting, while being served. This is so rude, yet it is common practice.

I’ve even seen this in the building society, when customers break off financial transactions to answer the phone, then have a lengthy chat, oblivious to the cashier and waiting customers.

Many adults are loathe to say thank you. I once helped a lost American tourist find her coach, driving around York for two hours until she finally recognised the drop-off spot and got out, without a word of thanks.

My daughter works in a cafe and says that, often, people never say thank you or even acknowledge her when she serves them or clears tables.

Almost on a daily basis I see adults dropping litter or throwing it from cars (with children in the back seats), I hear adults using foul language and see them spit in the street. In clothes shops I’ve seen adults pick up garments then drop them on the floor rather than hang them back up.

And how many adults do you know who love the sound of their own voice? I can name many who never listen to a word other people say, yet will spout on for hours about themselves. None of them are teenagers.

Teenagers do suffer from a sense of entitlement and crave overnight fame — which I blame squarely on the X-Factor. Having lived a little, adults thankfully lack this, but it does not stop them from being arrogant and rude.

As adults are the ones whose role it is to influence and inspire younger generations, surely it is them who need to learn some manners.