Rainboe,
many thanks for pointing me in the direction of the Questions board. I have not visited Pprune for a long time (and therefore did not know about the questions forum) due to the increasingly nitpicky and irrelevant nature of some of the posts, but thanks to your concern I now know it is there. I don't think my question is right for the Jetblast forum as it is actually something that could have a big impact on a professional pilot's ability to carry ou their job, and I know LOTS of pilots who would have an interest in this question - not least the amateur jockey/captain featured recently in Horse and Hound.