Which is the most important clock in the world? Many visitors to London would answer ‘Big Ben,’ even though this is officially the name of the bell behind it rather than the clock itself. However, as a London blue badge guide, I would say that the world’s most important timepiece is the John Harrison H4 which can be seen in the Greenwich Royal Observatory museum near where the Prime Meridian is marked on the ground.

Queen Elizabeth II is head of state of the United Kingdom and fifteen other countries. She is also a woman, a mother and was once a girl. Yet throughout her life all of that has come second to providing the symbolic value millions of people placed upon her.