No. BASC runs a medical panel of members who are registered medical practitioners. With your permission, they can obtain your notes from your GP and verify your medical declaration. There is a cost for this, but it is less than £60. Your GP cannot refuse to release your notes and has to release them within 30 days.
In his latest OffBeat blog, Bill Harriman discusses the reasoning behind BASC's support of medical markers for certificate holders.