The scenario that sets off the training is IMO, largely irrelevant. It is the practice for the response in the variety of conditions, co-ordination of responders, logistics, etc. etc. etc. that really counts.

That being said, it sounds like some bureaucrat somewhere had a list of things that needed to be trained/exercised, and, since this exercise was probably being planned at about the time of the Haiti earthquake, he/she had an a-ha moment and thought: "I know, a big earthquake here--it has everything we need."

Being a bureaucrat, he/she never thought to check on the history of British earthquakes.