Canada's Governor General David Johnston has blamed a "slippy" carpet for breaching royal etiquette in Queen Elizabeth's company.

Queen Elizabeth

Queen Elizabeth

The governor lightly touched the 91-year-old royal's elbow as she walked down the steps at an event in London to mark Canada's 150th birthday, however traditional "protocol" dictates that you should not touch the monarch unless she offers her hand.

He told CBC News: "Well I'm certainly conscious of the protocol.

"I was just anxious to be sure there was no stumbling on the steps."

The Queen visited Canada House with the Duke of Edinburgh and Johnston said he thought it was necessary to "breach protocol" and help them to avoid an accident.

He added: "It's a little bit awkward, that descent from Canada House to Trafalgar Square, and there was a carpet that was a little slippy, and so I thought perhaps it was appropriate to breach protocol just to be sure that there was no stumble."

According to the royal website, there are "no obligatory codes of behaviour when meeting the Queen or a member of the Royal Family, but many people wish to observe the traditional forms".

Some of those include a traditional form of greeting a royal, which for men is to bow from the head only while women carry out a small curtsy.

And the Queen should be adressed firstly as 'Your Majesty' and subsequently in conversation as 'Ma'am'.

In addition, when a monarch offers their hand and you should return this not with a firm handshake, but just a touch.

Queen Elizabeth likes to adhere to royal tradition and once told Lewis Hamilton off for his bad table manners.

The 30-year-old Formula 1 champion was invited to dine with Her Majesty, but has revealed that he was reprimanded for not knowing the correct protocol.

Lewis said: "I got invited to a lunch and was sitting next to The Queen. I was excited and started to talk to her but she said, pointing to my left, 'No, you speak that way first and I'll speak this way and then I'll come back to you.'"

Despite this telling off, Lewis went on to say that The Queen is "really cool".