My medical is a JAA Class 1 issued by the UK CAA at Gatwick. I've looked into the differences between the old CAA and new JAA and for my particular problem (astigmatism), the limits are the same. What I think has happened is that the NATS medical branch has taken one look at my prescription and made an immediate ruling without noticing that I already hold a Class 1 - something they're trying to tell me I will never be able to do.