CAP 493
Manual of Air Traffic Services Part 1
Section 1 Air Traffic Services
Chapter 4 Control of Traffic
Part 10 Flight Priorities
paragraph 10.3.1 Fuel Shortage and Medical Emergencies
Page 6
"D - Flights notified by the CAA carrying Heads of Government or very
senior government ministers."
This document is filled with delightful information. You can download it from the CAA website:
http://www.caa.co.uk/docs/33/CAP493Part1.pdf
Happy reading!