On a hot summer day in 1952, a 26-year-old called Elizabeth rode out of Buckingham Palace to take part in her first Trooping the Colour as Queen.
The new monarch was pictured sidesaddle on her chestnut horse, Winston, as she accepted the salute of her troops.
On the same day, with no fanfare, frigate HMS Plym slipped out of the Thames Estuary on a top secret mission which has kept Elizabeth, and her country, safe for seven decades.
