Thanks for your responses JetDriver.
I had my BP checked the week before and 2 days after by my GP and I was well within the FCL Class 1 limits. I have also been checking with a home kit periodically all within limits. On the day @ Gatwick the Dr had me down just over, but despite all of this info has insited on 24h Ambulatory. Hence the post. I didn't know the CAA had them, the letter I got said to go to my GP.
I'll give the Aeromedical section a call tommorrow - thanks.