One is rather chilly: Queen fends off the cold with a blanket in birthday parade

Wearing an aqua marine dress and matching hat, she topped off the look with a blue checked blanket draped across her lap.

Thousands of spectators joined the Queen and Duke of Edinburgh at the annual military spectacle that has been performed for decades at Horse Guards Parade in Whitehall.

Today's had an added poignancy coming the week that the death toll of British military personnel in Afghanistan passed 100.

The Queen and Prince Philip enjoy her official birthday celebrations in central London today

The Queen actual birthday was on April 21. Dressed in a turquoise green coat and matching hat, she watched with the Duke of Edinburgh, who wore a red military tunic and bearskin, as the ceremonial flag was paraded past her followed by line after line of Guardsmen, first in slow time then quick as the Massed Bands played.

The Guardsmen who took part today are fighting soldiers when not performing ceremonial duties, and many have either served in Iraq or Afghanistan, or will be deployed to the Middle East countries in the coming months.

The Queen's grandson Prince Harry - an officer in the Household Cavalry's Blues and Royals like his older brother William - also served in Afghanistan for 10 weeks at the beginning of the year.

Sunshine bathed Horse Guards Parade as the Queen arrived to play her important role in a ceremony that she has attended every year since her accession to the throne in 1952, except in 1955 when there was a national rail strike.

Her first duty was to inspect the long line of troops - wearing their famous red tunics and bearskin hats - from the four Foot Guards regiments of the Household Division taking part - the Welsh, Grenadier, Scots and Coldstream Guards.

As she travelled in an 1842 ivory mounted phaeton carriage, behind her on horseback and wearing ceremonial military uniform were the Prince of Wales, who is Colonel of the Welsh Guards, the Princess Royal, Colonel Blues and Royals, and the Duke of Kent, Colonel Scots Guards.

Prince William (left), stepmother Camilla, the Duchess of Cornwall, and Prince Harry leave Buckingham Palace for the ceremony

The Duchess of Cornwall, and William and Harry - both in military uniform - watched from a room in Horse Guards building that used to be the Duke of Wellington's office.

They were joined by the Earl and Countess of Wessex and the Duke and Duchess of Gloucester.

Other guests watching the spectacle were Prime Minister Gordon Brown and his wife Sarah.

Henry Allingham, Europe's oldest man at 112, and one of three British survivors of the First World War, was also present.

Trooping the Colour originated from traditional preparations for battle. Colours, or flags, were carried, or 'trooped', down the ranks so that it could be seen and recognised by the soldiers. The Colour being paraded on Horse Guards this year was the flag of the 1st Battalion Welsh Guards.

The duty of carrying the colour was given to Lieutenant Henry Finnegan who was commissioned into the Welsh Guards in August last year.

Later the Mounted Bands of the Household Cavalry played as the King's Troop Royal Horse Artillery, commanded by Major Erica Bridge - the first woman to hold the post - rode past the Queen first in quick time then in slow.

As they passed for the second time the horses' hoofs kicked up clouds of dust from the gravel-covered parade ground.

When the Queen and the Duke left in their carriage they were applauded by the spectators and those lining the Mall as they made their way back to Buckingham Palace.