New official photographs have been released, showing the Queen at her desk
Queen Elizabeth II
becomes Britain's longest-reigning monarch later when she passes the
record set by her great-great-grandmother Queen Victoria.
The
Queen will have reigned for 63 years and seven months - calculated at
23,226 days, 16 hours and approximately 30 minutes at about 17:30 BST.
Prime Minister David Cameron will lead tributes in the House of Commons and there will be a
River Thames salute.
The Queen, who is 89, will spend the day on official duties in Scotland.
The
exact moment the Queen reaches the milestone is not known because her
father, George VI, passed away in the early hours of 6 February 1952.
Business in the Commons will be postponed for half an hour so MPs can pay tribute to the Queen.
On
the Thames, a flotilla of historic vessels, leisure cruisers and
passenger boats will take part in a procession between Tower Bridge and
the Houses of Parliament.
The bridge will lift as a sign of respect and HMS Belfast will sound a four-gun salute.
The BT Tower in central London will scroll the message "Long may she reign".
Analysis
By BBC royal correspondent Nicholas Witchell
It will be day 23,226 of her reign. The Queen is determined that it should in no way be exceptional.
She has let it be known with some emphasis that she does not want a fuss to be made.
It
is evidently viewed as 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.
But of course that is precisely why 9 September
2015 is notable in its way. Elizabeth II will become the
longest-reigning monarch in British history, passing the record set by
her great-great-grandmother Victoria.
And in an institution as old
as the monarchy, that is a rather striking measure to add to the other
memorable features of her reign.
She may not want there to be a
fuss but it would seem that a good number of British citizens, to say
nothing of those from further afield, believe that her record-breaking
reign deserves a little recognition.
A constant amid gale-force changes
Buckingham
Palace has released an official photograph to mark the occasion, taken
by Mary McCartney in the Queen's private audience room.
This is where she holds weekly audiences with prime ministers of the day, and receives visiting heads of state and government.
The prime minister's official spokeswoman said Mr Cameron had paid tribute to the Queen at a cabinet meeting on Monday.
Mr Cameron said the Queen had a "remarkable record" and was "a symbol of Britain's enduring spirit admired around the world".
It is understood that Wednesday will be a normal working day for the monarch with no special celebration.
She
will be joined by the Duke of Edinburgh to open the £294m Scottish
Borders Railway and make a steam train journey with Scotland's First
Minister Nicola Sturgeon.
The Queen is taking her traditional summer break at this time of year at her private Scottish home, Balmoral.
Queens of the modern age
Elizabeth II has reigned for 63 years and seven months, beating Queen Victoria's record
- Victoria became queen at 18 while Elizabeth was 25
- Elizabeth II rides in the same coach as Victoria did for the annual State Opening of Parliament
- Both queens were shot at by a lone gunman while out riding near Buckingham Palace
- Elizabeth loves the private royal estate at Balmoral, which was bought by Victoria
- Victoria ruled over an empire of 400 million people. Elizabeth is head of state for 138 million people
Queen Victoria became queen at the age of 18 and ruled for 63 years, seven months and two days.
Queen Elizabeth's reign has included 12 prime ministers, two more than served under Victoria.
One
of those prime ministers, Conservative Sir John Major, rejected any
suggestion the Queen had been too passive as head of state: "The
monarchy wouldn't be as popular if they were part of politics - they're
above and beyond it.
"But when the Queen meets her prime minister
she has the opportunity to question, to ask, to counsel. Nobody knows
and no prime minister is going to tell you exactly what happens at those
meetings. So those who say she's been too passive, how can they
possibly know?"
The Queen is sovereign of 15 Commonwealth realms
in addition to the UK, and Brian Mulroney, former prime minister of
Canada, said she remained extremely popular there.
'Genuinely exceptional'
He
also told BBC Radio 5live that while her position might appear only
"symbolic", she had played an important role on the world stage, notably
in the fight against apartheid in South Africa.
"She has her own
way of conveying a view on an important national or international issue
that, if you know her in any way, is unmistakeably clear.
"The
fact that she has exercised authority in such an impeccable manner, her
own reputation and her own personal conduct has been flawless... the
only conclusion I can come to is that she is a genuinely exceptional
person."
The new photographs show the Queen with her official
red box, containing the day's policy papers, cabinet documents, Foreign
Office telegrams and other letters
Anti-monarchist group Republic said the Queen's long reign was a reason for reform not celebration.
Chief
executive Graham Smith said: "It is now time for the country to look to
the future and to choose a successor through free and fair elections,
someone who can genuinely represent the nation."
