Queen's 90th birthday: Cameron and Corbyn lead tributes
David Cameron and Jeremy Corbyn have led tributes to the Queen in the House of Commons as MPs marked her 90th birthday.
Opening a special "Humble Address", the PM said she had led a "gentle evolution" of the monarchy during her 64-year reign.
Labour leader Jeremy Corbyn said whatever people's views on the monarchy, the "vast majority" agreed she had served her country.
UK-wide celebrations are taking place.
Crowds lined the streets in Windsor as the monarch took part in a walkabout, after royal gun salutes were fired from each of the UK's capital cities.
Mr Cameron paid tribute to her "extraordinary service", which he said was "a joy for us all to celebrate, to cherish and to honour".
He added: "In this modern Elizabethan era, Her Majesty has led a gentle evolution of our monarchy.
"From that first televised Christmas Day message, over three decades before cameras were allowed into this House, to the opening up of the royal palaces and the invention of the royal walkabout, she's brought the monarchy closer to the people while also retaining its dignity."
Praising her international diplomacy, the PM said that after a visit to Balmoral, the Queen could claim to be the only woman to have ever driven the King of Saudi Arabia around in a car.
Mr Corbyn, who has said he is a Republican "at heart" but is not interested in trying to replace the monarchy, offered the Queen his "warmest greetings" and said he was "fully in favour of our country having leaders of a finer vintage".
"Today we're talking about a highly respected individual who is 90 - and whatever different views people across this country have about the institution, the vast majority share an opinion that Her Majesty has served this country and has overwhelming support with a clear sense of public service and public duty," he said, before joking that she may be, like him, an Arsenal fan.
Angus Robertson, the SNP's Westminster leader, highlighted the Queen's "enduring and special" relationship with Scotland, and recalled her opening of the Scottish Parliament in 1999 "after a recess of nearly 300 years".
"I'd like to take the opportunity to put on record the appreciation of people in Scotland to Her Majesty, who has had a lifetime connection with and a commitment to the country," he said.
Liberal Democrat Leader Tim Farron she had provided "immeasurable constancy" during a time of great upheaval.