Goodness - I imagine you must be quite popular when you go travelling!

Well, I guess I can be considered to be "abroad" since the vast majority of my meals are eaten in the UK and Europe.

The tipping culture is far less ingrained in the UK and even less in Europe. In fact, it's starting to make encroachments in recent years, much to the chagrin of many people. It's seen as another way for restaurants to line their pockets and, to be honest, this view isn't entirely wrong. It's also seen as the UK adopting an American-style "tip-for-everything" culture, which as you can imagine isn't universally popular.

I tip when it's appropriate. If someone helps me with my luggage, they'll get a tip. If someone serves me food and, they'll usually get a tip. This is usually between 5 and 10% of the bill - which is entirely normal.

In the past five years, it has become much more common for restaurants in the UK to add an "optional" 10-12.5% service charge to every bill. This is actually indeed optional, but you generally pay it unless you want to look like a cad. Very, very occasionally I have been with parties where the service has been so awful, we have refused to pay the service charge. I actually have no problem with this, as as far as I'm concerned, if it's optional, then it's optional.

There was an expose a few months ago which showed that some restaurants routinely keep a portion of the service charge for themselves. I believe that this was designated as "administrative fees" or some such bee-ess. One major chain was Pizza Express - where I have literally not returned since hearing that they kept 20% of all tips.

Anyway, I only tip where appropriate, have no problem tipping generously where deserved, but baulk when it is suggested that servers in particular are entitled to at least 15%. IMHO, they are entitled to 15% if I am entitled to good service. If they don't live up to their side of the bargain, neither do I.