The Suez crisis was building in the northern summer of 1956.
My father, Tom McLeod, was serving as a Wireless/Telegraph Officer in the RAAF Queen's Flight in UK at the time. The crew were responsible for flying the Royal Family and other visiting VIP's around Europe.
On June 15th 1956, the crew flew the Australian Prime Minister, the Right Honorable R.G. Menzies and the Prime Minister of Malta from Luqa, Malta, to Orly, Paris. The log book entry can be seen
During a flyover of the P&O Royal Mail Ship "Arcadia" Menzies asked my father to send a message to the Commodore of the Arcadia:
"Commodore - RMS Arcadia Greetings and best wishes to all on board (stop) The ship looks much smaller from here... Menzies Party"
Menzies drafted the message on the back of an envelope which had been sent to him by the Chief Justice in Sydney, on June 5th 1956.
The envelope was addressed and marked "personal".
The two stamps are Australian one shilling lyrebird stamps.