In a ceremony outside Buckingham Palace, the queen placed a hand-written secret message inside the baton. The relay will cover 123,000 miles (198,000 kms), passing through 70 nations and territories before the queen reads her message to the athletes at the opening ceremony at Celtic Park on July 23.
Dressed in a kilt and walking to the sound of bagpipes, retired Scottish cyclist Chris Hoy Britain's most decorated Olympian carried the baton down The Mall before passing it to the queen.
The baton heads first to Scotland and then goes to India.
