The aristocrat, who is also Elizabeth II’s distant cousin, told Brandreth: “She said…’I would like Lord Ivar’s guns to be up here tomorrow morning. Please see to it’.

“Whereupon she turns back to me and she looks at me over her glasses with a glint in her eye and she says ‘They want me to open their new terminal’. She says ‘I don’t think I will now’.”

Lord Mountbatten added: “So every time I go back to Bristol Airport now, it was opened by the Princess Royal, I have a quiet laugh to myself.”

The Princess Royal first opened a terminal building at Bristol Airport in 2000, and later opened a terminal extension in 2015.