Crowds gather for Queen Mother

Town criers Steve Clow and Peter Baker ring a greeting

The Queen Mother will celebrate her 100th birthday in grand style on Friday, becoming the Royal Family's first centenarian.

In a day of festivities, she will take the nation's salute from the balcony of Buckingham Palace.

Click here from 1045GMT/1145BST to see BBC News Online's live coverage of the Queen Mother celebrations.

She will be cheered by thousands of well-wishers, many of who have camped overnight to ensure they are part of the historic occasion.

Hats off to the Queen Mum: Connie Nisinger has travelled from the USA

To mark her mother's 100th birthday, the Queen has issued a special Honours List recognising nine people, five of whom helped stage the Queen Mother's centenary pageant last month.

The Queen Mother's life has spanned the milestones of the 20th Century and embraced a new millennium.

As possibly the best-loved member of the Royal Family she has been a symbol of grace in an era of upheaval for many millions.

Large numbers of people - from Britain and overseas - are gathering outside Clarence House, Buckingham Palace and along The Mall to catch a glimpse of her.

But the public will have to wait until nearly midday before their first sight of her.

'Happy Birthday'

She is expected to appear at the gates of Clarence House at 1145 BST.

Only residents and staff at Clarence House and adjoining St James's Palace will be able to see her outside the main gates, but selected media will beam TV pictures to expectant viewers around the world.

The Queen Mother's life has spanned the 20th Century

The Queen Mother will take the salute from the King's Troop Royal Horse Artillery riding by Clarence House and the and of the Irish Guards will march past playing Happy Birthday, followed by the Grenadier Guards.

A Royal Mail postman will arrive to deliver a 100th birthday card from the Queen, containing a handwritten message.

The Queen Mother will then leave Clarence House for Buckingham Palace in a an open carriage accompanied by her grandson, the Prince of Wales.

Her ladies-in-waiting will be at Clarence House Garden Gate, on The Mall, during Friday morning to receive flowers, gifts or cards from well-wishers.

Gun salute

More than 30 members of the Royal Family will be at Buckingham Palace for a private birthday lunch in the magnificent Bow Room.

All the senior royals are expected to be there, including great-grandchildren Prince William, 18, and Prince Harry, 15.

As the Queen Mother appears on the Palace balcony to take the nation's salute, a 100th birthday gun salute will be fired from nearby Green Park.

A card from the Queen will be delivered to her mother

Uniquely, the 41-gun royal salute will begin when she steps out on to the balcony and not at 12 noon as is normal practice.

The Queen and other members of the Royal Family are expected to join the Queen Mother on the balcony.

During past birthdays, she has met members of the public outside Clarence House, but this year's carriage ride and balcony appearance will allow more people to see her.

The balcony salute will be the climax of protracted centenary celebrations which have lasted several weeks.

On 21 June, there was a Royal birthday party at Windsor Castle and since then there have been a host of public tributes.

Scottish salute

Elsewhere around the UK, final birthday event preparations have been put in place.

Glamis Castle, near Dundee in Scotland, where the Queen Mother spent much of her childhood will also host a day's celebrations in honour of her 100th birthday.

The centenary festivities in Scotland will also include the issuing of two million specially-produced Royal Bank of Scotland £20 notes showing pictures of her now and when she was a child.

Visitors to Stirling Castle will also be able to enjoy a slice of a giant birthday cake prepared by Historic Scotland.