At Balmoral, Queen Elizabeth often joked, 'joining in, singing dirty songs'

On duty she sometimes found it hard to keep a straight face when ceremonial turned to near-comedy

The Duchess of Cambridge laughs as the Queen gestures while they watch part of a children’s sports event during a visit to Vernon Park in Nottingham (Phil Noble/PA)

Being head of state was a serious business, but the Queen had a lighter side and a playful sense of humour.

She was a talented mimic, as was her mother and, in private, was known to turn her skill on the rich and famous.