tipping cabs in London

I tip London cabs about 20%, if all went well.

For that journey, a flat five pounds if the driver helps with luggage. Otherwise for general rides one or two pounds rounded to the nearest pound.

As Linda said.

I've been in numerous London cabs. They tend to be very roomy, with enough space for about 4 people. If you are traveling light, you will probably just place your own luggage in the passenger compartment. The "cabbie" won't need to help you. I pay the metered fare and round it up a little, but not by much.

Surveys quoted by Her Majesty's Revenue and Customs suggest the average tip in a taxi in the UK is about 9%, although this has if anything declined a little in recent years. When it comes to it though, it is the experience that should determine it of course.

My answer was based on the assumption that the pre-ordered cab is a private car transfer service rather than a metered London "black" cab. A much cheaper option!