LONDON (AP) — Canada's governor general says he decided to breach royal protocol and touch Queen Elizabeth II to ensure she didn't stumble down slippery steps during an official engagement in London.

David Johnston, who met with the 91-year-old monarch on Wednesday to mark Canada's 150th birthday, was seen gently touching her elbow as she ascended steps at London's Canada House. He did the same as she left the building.

It is generally accepted that members of the public do not touch the queen.

Johnston told CBC News: "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."