It is simply not the done thing. Or to put it another way, you can look but you can’t touch.

So much so that Canada’s Governor General has felt the need to explained why he decided to breach royal protocol and touch the Queen, saying that he wanted to make sure she did not slip during an official engagement.

David Johnston was spotted supporting the 91-year-old by gently touching her elbow as she climbed the steps at Canada House in Trafalgar Square, on Wednesday.