British prime ministers must wonder why they bother to go on holiday, particularly to Tuscany.

"Tuscan Tony" Blair became seriously unpopular with the locals during his summer sojourns in Britain's favourite part of Italy. Now David Cameron, just two days into his Tuscan break, is in trouble because he did not tip a cafe waitress who was "too busy" to bring the coffees he had ordered to his outside table.

Mr Cameron had received plaudits for paying (unlike you know who) for his holiday villa, which is costing almost £6000 for two weeks. But if he can afford that kind of money for his villa, why can't he give a modest tip to a waitress who is no doubt not especially well paid?

I've some sympathy for Mr Cameron here. If the server was "too busy" to bring the coffees from the bar counter to the Camerons' table, I'm not sure she deserved any tip. And as the total bill was just over three Euros, 10% of that would hardly have been a significant sum. I think where the Prime Minister gaffed was in paying such a small bill with a 50 Euro note. It can be infuriating when people spend small but pay big, necessitating a vast amount of change.

Tipping is more prevalent today than it was when I was young, but there is huge confusion about who should be tipped and who shouldn't. Some people in the service industries still regard it as demeaning to be offered a tip.

My wife regularly informs me that I tip too generously, particularly to taxi drivers. Maybe, but this goes back a long time – in my youth I had a holiday job as a taxi driver in Aberdeen. Only for a few weeks, and although it was a bona fide company, the cabs were not licensed to pick up in the streets or at the station. Even so I learned a lot in that short time. I became very grateful to solid tippers (and yes, there were plenty of those in Aberdeen). Usually they were the most trouble-free and pleasant fares.

People going to weddings tended to be mean; people going to funerals were particularly generous. The worst experience I had was at a wedding when I had to pick up the bride and groom from the reception at a small suburban hotel, and drive them to their train. I arrived on time but the best man told me to come back 10 minutes later as he was organising a "reception committee" for the honeymoon couple at the station.

When we eventually arrived at the station the cab was mobbed and showered with confetti and other less pleasant substances. Later it took me an hour to clean it. The happy couple jumped out and skedaddled off through the rowdy pranksters. Without paying, of course. I had to seek out the best man who reluctantly paid the fare. No question of a tip.

Tipping is replete with complications and delicacy. Many years ago it was assumed you'd tip your postie at Christmas. But then you had the same postie, year in year out. Now they seem to change on a weekly basis (as do the delivery times). So posties just don't get tipped at Christmas any more.

I gather that women of a certain generation generally tip their hair stylists, but are unsure whether they should also tip the girl who washes their hair (and who is probably paid a pittance).

In restaurants, I like to tip quite well if the service and the meal have been at all good. When paying by credit card I insist on paying only the bill itself by plastic, and leave the tip in cash.

The waiter or waitress may never see the gratuity otherwise – and even if they do, it may take weeks to materialise.

There seem to be no generally accepted rules, no agreed etiquette.

What should be a small kindness, a mark of appreciation, causes too much tension and confusion, especially when people are on holiday.