That draws our live page to a close on the day the Queen turned 90.

Here is a recap of what happened today:

• The Queen met crowds of people in Windsor and unveiled a plaque for a digital walking trail
• She then took part in a walkabout of the town and greeted well-wishers with her husband Prince Philip, also travelling in an open-top car
• Prime Minister David Cameron led the tributes to the Queen, describing her as "a rock of strength for our nation"
• Prince Charles paid tribute to his mother in a special broadcast and later when she lit a beacon
• The Queen lit a beacon at Windsor Castle, the first in a series of more than 900 being lit across the UK and overseas to mark the day

Image source, AFP/Getty Images

BBC News Channel

Dicky Arbiter, the former press secretary to the Queen, said he thought more people had turned out for the Queen's birthday than when she was 80. 

He said he thought the Queen "looked like she was enjoying every single minute" of the day.  

Asked about the private dinner the Queen is to have at Windsor Castle, Dicky said "the whole family will be there".  

The Queen is returning to Windsor Castle after lighting the first in a series of more than 900 beacons that are being lit across the UK and overseas. 

But before leaving she was treated to a performance of God Save the Queen and got the chance to see the beacon fully lit.  

Beacons are also being lit across the UK.

The beacon lit by the Queen in Windsor burns bright, as more than 900 others are lit across the UK and overseas to mark the monarch's birthday. 

Following that birthday message from Prince Charles, the Queen has just lit the first beacon.

More than 900 beacons will be now lit across the UK, Channel Islands, Isle of Man and British Overseas Territories. 

The prince then called on the crowds to give three cheers for the Queen. 

"If they're loud enough it might just work to light the other beacons by spontaneous combustion," he joked.  

Prince Charles has been paying tribute to his mother the Queen on her 90th birthday.

He said: "I find it very hard to believe that you’ve reached your 90th year and I suddenly realised the other day that I have known you since you were 22 years old. But this ladies and gentleman is a very special occasion and the beacon that her majesty is about to light will also represent as it lights other beacons across the nation the love and affection with which you are held throughout this country and the Commonwealth. 

"So can we wish your majesty a special and the most happiest of birthdays on this occasion."

The Duke and Duchess of Cornwall have arrived outside Windsor Castle, moments before the Queen lights the first of more than 900 beacons across the UK. 

Prince Charles is to give a speech before the beacon is lit. 

The Queen is expected to appear shortly. 

Image source, AP

The BBC's royal correspondent Nicholas Witchell said the impression he had was that the Queen was "really enjoying the day". 

He said he thought she had reached the stage where she was more relaxed in her role and could appreciate the "praise and affection" of wellwishers.

Our correspondent added: 

Crowds are once again growing in Windsor ahead of the Queen lighting a beacon as part of her birthday celebrations. 

More than 900 beacons will be lit afterwards in locations across the UK and overseas. 

The Queen is due to light a beacon in a little over one hour, after which more than 900 will be lit across the UK and overseas.   

Local authorities around the UK will host lighting events throughout the country to create a network of flames in celebration. 

Members of the Army Cadet Force will be taking beacons to the top of the four highest peaks in the United Kingdom - Ben Nevis in Scotland, Mount Snowdon in Wales, Scafell Pike in England, and Slieve Donard in Northern Ireland. 

In a written message to beacon lighters, Prince Charles said: