Just like King Charles and the Prince and Princess of Wales, Queen Elizabeth II had to attend tens – if not over 100 – royal engagements a year during her lifetime. Although polite and friendly while meeting both the public and those in high places, even the Queen had a social threshold.

It’s important to have boundaries no matter who you are or who you’re with, and Queen Elizabeth clearly had hers. She knew when she had had enough of socialising, and when it was her cue to leave.

However, it was important to the late monarch not to make it too obvious that she desired to leave a social engagement.

Ian Scott Hunter, who worked as Her Majesty’s footman for eight years, revealed a secret code the Queen used to make her staff aware that, for her, an event or engagement was coming to an end.

In a special episode of Antiques Roadshow, on board the Royal Yacht Britannia, Ian said the late monarch used her make-up as a means of communicating with her ladies-in-waiting.

He explained: “I believe there’s etiquette that ladies do not make their faces up in public.

“But she [the Queen] had her bag over the side and she would take her lipstick out and put it on with no mirror or anything, and that was a signal to the ladies that she was ready to leave.”

Once the Queen’s staff saw her lipstick, they knew a swift exit would follow.

Ian continued: “Of course, they [the ladies-in-waiting] would all get their bits and bobs together and Her Majesty [would] stand up, so they’re all ready and prepared.”

But this wasn’t the only social cue the Queen had at her disposal during her lifetime.

Royal commentator Kristen Meinzer shared that the Queen would swap her handbag from arm to arm to politely convey she wanted to end a conversation.

Speaking on Newsweek’s The Royal Report podcast, Kristen said: “Supposedly if she’s standing around at an event and mingling with people and talking, and she switches her handbag from one arm to the other, she’s telling her staff she’d like someone to interrupt and end the conversation.”

A similar technique was practised when she would want to leave a banquet or formal dinner.

Historian Hugo Vickers told People that the Queen would place her bag on the floor if she wanted to go home. Before that, it would be on the table – acting as a five-minute warning.

Hugo said: “It would be very worrying if you were talking to the Queen and saw the handbag move from one hand to the other. It would be done very nicely.

“Someone would come along and say, ‘Sir, the Archbishop of Canterbury would very much like to meet you’.”

The Queen is believed to have owned more than 200 Launer handbags, her preferred styles being the Royale and the black patent Traviata.

But it wasn’t only her bag that was used to enact her escapes, but also her wedding ring.

While he was Prince of Wales, even Charles had a trick or two up his sleeve to end a conversation.

Hugo added: “What they all do is try to find a quick joke to leave it on.

“Prince Charles [at the time] has a quick ‘ha ha’ and that enables him to break the conversation.”