Queen Elizabeth II becomes longest reigning monarch
Queen Elizabeth II became Britain's longest-ruling monarch as she surpassed the historic record set by Queen Victoria, her great-great-grandmother.
The Queen's reign which began on 6 February 1952 has extended for 63 years and seven months.
The Queen will be on official duties in Scotland on this historic event.
PM Cameron called the Queen ""a symbol of Britain's enduring spirit admired around the world".
23 Sep 1896: Like grandmother, like grand-daughter
Queen Victoria became Britain's longest reigning monarch on 23 September 1896.
The present queen's grandmother inherited the crown at the age of 18.
Queen Victoria ruled over an almost 400 million large population under the crown for 63 years, seven months, and two days.
Interestingly, both monarchs were fired at by a solitary gunman while out riding near the Buckingham Palace.
1936: From 3rd in line to 'heir presumptive'
At the time of birth, Elizabeth was third in the succession line to the throne after her uncle Edward, Prince of Wales and father, the Duke of York.
In 1936, after her grandfather's death, Edward VIII became King.
However later that year, King Edward abdicated following his proposed marriage to Wallis Simpson, a divorcee.
Elizabeth's father became king and she became 'heir presumptive'.
Fact: A coronation like none other
Queen Elizabeth II's coronation was watched by an estimated 27 million people on TV and 11 million listened on the radio while 400,000 had witnessed her grand-mother's coronation.
9 Sep 2015: One Monarch, several feats
Queen Elizabeth II is the "longest reigning female monarch" in world history.
The then Princess Elizabeth and Lieutenant Philip Mountbatten were married on November 1947 and theirs has been the longest royal marriage.
Queen Elizabeth II is the oldest living monarch and has two birthdays.
As the head of state of 16 Commonwealth states, her portrait is on the maximum number of currencies.
9 Sep 2015: Queen Elizabeth II becomes longest reigning monarch
Fact: The Queen wants the day to be un-exceptional
The Queen has asked that the day be treated like any other day as it is considered "bad form for one long-lived queen to be seen in any way to be celebrating the passing of a record set by another long-lived queen."
9 Sep 2015: Tribute to mark the historic event
All business in the House of Commons is to be postponed while the MPs pay tribute to the Queen.
A procession between Tower Bridge and the Houses of Parliament where a flotilla parade of historic vessels, leisure cruisers and passenger boats will take place.
As sign of respect, the Tower bridge will be lifted; a four-gun salute will be sounded at HMS Belfast.