The Queen puts pen to paper - the special greetings she sends out are typewritten before being signed
The delivery of the cards has been going on for over a century but became a regular event in 1917 - the first year statistics were kept. Then, the Queen's grandather, George V, sent out 24 congratulatory messages to centenarians. In 2011, Elizabeth II sent out 9,736. It is a useful reminder of the changing nature of society with better health and better health care and living conditions meaning that more and more people are making their century. The cards are also sent to citizens of 'Her Realms and UK Overseas Territories' and the oldest ever receipient was a man in Canada who celebrated reaching 116 years of age.
George V was the first British monarch to regularly send birthday greetings to his fellow citizens when they reached 100
The Anniversaries Office is repsonsible for sending out the cards and gets information on people's ages from the state pension database but it does welcome applications from members of the public who want to make sure their loved one is on the list. And it holds no information on marriage anniversaries so anyone wanting to make sure those special dates are marked needs to write in. The applications must be sent no earlier than three weeks before the date of the event with full details available on the British Monarchy website. In just three years time this special celebration will reach an anniversary of its own. And thousands more will have enjoyed an extra special moment on their big day as they get their telegram from the Queen.