Very legal
Insert after Article 21 of Principal Order :
21 A
(1) Subject as hereinafter provided, the Civil Aviation Ensign, established by Civil Aviation Ensign Order 1937, shall not be flown on any aircraft or on any ship or boat or on any building or elsewhere in the UK.
(2) Civil Aviation Ensign may be flown :
(a) by any aircraft registered in the United Kingdom.
(b) at any aerodrome in the United Kingdom licenced under Air Navigation Acts 1920 and 1936.
(c) by a person operating an Air Transport operation owning aircraft registered in the United Kingdom upon or in proximity to any building occupied by him as his principal office or place of business.
(d) by any person to whom permission is granted by the Secretary of State at such places and subject to such conditions as may be specified in such permission, provided that it shall not be hoisted on any ship or boat belonging to a British subject without warrant from His Majesty or Admiralty.
I hope we can resurrect its use in GA, but I was not going to start shouting about it until my MCR is finished early next year.
Rod1