Queen Elizabeth II becomes Britain's longest-reigning monarch
Prime Minister David Cameron leads tributes in the House of Commons
The Queen makes a brief speech as she opens Scotland's new Borders Railway
She says: "A long life can pass by many milestones. My own is no exception."
The record was held by her great-great-grandmother Queen Victoria
A flotilla of historic vessels, leisure cruisers and passenger boats take part in a procession on the Thames
The many well-wishers that the Queen has do not include Graham Smith, a campaigner from the group Republic, which campaigns for the abolition of the monarchy and calls for a directly-elected head of state.
In a personal film for Daily Politics, he says the monarchy is "wrong for pragmatic, principled and political reasons".
Image source, PAThe flotilla down the Thames to mark the Queen's special day is under way. Tower Bridge has been raised as the vessels came through. HMS Belfast sounded and has fired a gun salute four times as the flotilla makes its way past.
Image source, Getty ImagesTweedbank Station was packed with well-wishers
Image source, Getty ImagesChildren wave union flags as they wait for the Queen
Image source, ReutersA pipe band performed at Waverley Station ahead of the Queen's arrival
A BBC Royal Correspondent tweets:
Transport Scotland tweets:
Queen leaves Edinburgh on steam train
Cheering crowds greeted the Queen in Edinburgh on the day she becomes Britain's longest reigning monarch.
Bad weather delayed her arrival at Waverley Station, but the 89-year-old Queen - wearing a two-tone blue coat and matching hat - and the Duke of Edinburgh eventually set off on the new Borders Railway.
Labour leader Harriet Harman says: "Her life has been a great sweep of British history and it is no exaggeration to say that she is admired by billions of people around the world".
The acting Labour leader causes amusement in the chamber by remarking that Her Majesty is now on her 12th prime minister "although we on these benches had hoped she would now be on her 13th".
Ms Harman provokes another burst of laughter when she says "the Queen reigns over 140 million people - that's nearly as many as the number of the Labour Party's registered supporters".
The royal party has stopped off at Newtongrange in Midlothian, during her journey down the new Scottish Borders Railway. Her Majesty has been given plenty of bouquets by well-wishers during her walkabout.
The acting leader of the Labour Party, Harriet Harman, tells the Commons: "It is entirely characteristic of her that she has let it be known that she doesn't want there to be a fuss made about today but we are making a fuss and deservedly so.
"We send her our warmest congratulations, our appreciation and above all our thanks.
"There can be no doubt of her commitment. Even today at the age of 89, she's undertaking a public engagement."
Mr Cameron continues his tribute, saying Her Majesty has played a leading role in building a "family of nations". As a diplomat and ambassador, it's hard to overstate what she's done for this country, he adds.
He also says how people see time and again how her words can build partnerships, and how she's held in deep affection by leaders around the world.
A BBC Scotland journalist tweets:
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The Queen's long reign: Soldier's memories of first investiture
Just three weeks after Princess Elizabeth became Queen, Bill Speakman went to Buckingham Palace to be awarded the Victoria Cross, in the first investiture of the Queen's reign.
He received the VC for holding off a wave of attacks in the Korean War.
Now 91, Mr Speakman told BBC Radio 5 live Daily's Peter Allen what he remembers of meeting the Queen that day.
We are expecting parliamentary tributes to the Queen in the House of Lords to start at 14:30 BST. This will be led by Baroness Stowell, Leader of the House of Lords.
David Cameron is speaking now in the House of Commons, and tells MPs it is "truly humbling" to comprehend the scale of service that the Queen has given this country.
Image source, PAThe Queen was all smiles as she was handed a posy of flowers before getting on board the train. She is wearing a turquoise and blue outfit - accessorised by her trusty black handbag.
The Queen and Prince Philip, with Scottish First Minister Nicola Sturgeon, are all now aboard the Pegasus Pullman steam train, chugging their way down the new £294m Scottish Borders Railway towards Tweedbank.
BBC Scotland reporter tweets:
The Queen is set to open the new £294m Scottish Borders Railway. The royal party will travel the new route, stopping at Newtongrange in Midlothian before carrying on to the final station, the Borders town of Tweedbank, where the opening ceremony will be held.
The Queen and Prince Philip shook hands with Scotland's First Minister Nicola Sturgeon before getting on board the Pegasus Pullman steam train that will take them to Tweedbank. They are now on their way down the railway line.