It was the crinkly handshake that did it. Bill the American had just said “thank you” after a two-hour walk in Glen Nevis to a guide who was so much fun that it felt as if we were hiking with a friend. Feeling awkward about handing over money to a mate, I just smiled. But the guilt kicked in.

Back on the Royal Scotsman, which had arranged the excursion, my tipping angst heightened as the luxury train trip neared its end. When the bill for three nights comes in at £2,500, how much are you supposed to hand over? A £50 note suddenly seemed stingy.

So I fluffed it, even though I had rarely come across service more deserving of a little extra financial recognition.

I am what you would call a reluctant tipper. For a start, there is the awkwardness - the who, the how, and the how much (I'll never forget the humiliated look on the Sri Lankan marketing executive's face after I proferred some notes when she showed me to my room). So unless I'm in a developing country, where little and often is my motto, I play avoidance tactics despite our burgeoning tipping culture.

Not even the most assiduous bellboy can prise my suitcase from my grip and carry it to the room. If I order breakfast in bed (often already subject to a “tray charge”), I reason that I can hardly be expected to conjure money from the pocket of my dressing gown.

But there is also the question of whether a tip is deserved. Let's not forget what it signifies: a reward for a job well done. (How did the word originate? Not, as popularly thought, as an acronymn for To Improve Prompt Service. The Oxford English Dictionary says that the term is derived from the old English gamblers' slang expression tip, meaning “to pass from one to another”.)

I know that many staff rely on these little extras to make up their meagre wages, but why can't companies pay their employees a decent whack in the first place, not levy us with an unofficial service charge?

In any case, service charges and tips are not the same thing, as the Norwegian Cruise Line spells out in its promotional material, which explains that service charges of $10 a day are automatically added to customers' accounts. NCL then trumpets that tipping is neither required nor recommended, but says that because staff are encouraged to “go the extra mile”, they can accept discretionary cash gratuities. Talk about a double whammy.

When a tip is deserved, though, it's the how much that causes consternation among British travellers (why can't more companies, like Seabourn cruises, include tips in the upfront cost - oh, the relief of a guiltless, tip-free trip.)

If you're more generous than me, feel moved to burrow in your pocket by staff hovering at your hotel room door, or really want to reward good service, here are the results of my research on tipping guidelines: The Dorchester - bellboy, £1-£2; doorman, 50p-£1; P&O Cruise, £3.75 a night; safari ranger on an Abercrombie & Kent tour, $10 a day; First Choice holiday rep - nothing.

And the Royal Scotsman? It appears that £75pp would have done the trick. So to the excellent staff on board, a hearty apology; the drinks are on me next time we meet.

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