It was really strange for me when I started to play concerts in America where the audiences were all sitting down.

There are signs that the age of petroleum has passed its zenith. Adjusted for inflation, a barrel of crude oil now sells for three times its long-run average. The large western oil companies, which cartellised the industry for much of the 20th century, are now selling more oil than they find, and are thus in the throes of liquidation.

So Harry Potter came in and it is nice that I have kids of the right age. I took them to London and they walked around the set and met Harry Potter and that is thrilling.

One of my grandfathers, actually, having gone out there as a minister, decided he would better serve the people as a doctor. So at a very late age - at the age of 38 in fact - he changed course and decided to become a doctor.