With the uniquely colorful and ostentatious pageantry that still cheers this country in its post-imperial days, Britain enthusiastically celebrated today the 80th birthday of the beloved grand dame of its royal family, the Queen Mother Elizabeth.

The widow of the late King George VI and the mother of the present Queen Elizabeth II, she is remembered for helping her shy husband warm to his unexpected task of becoming king in 1937, revered for risking her personal safety in her efforts to keep up the country's morale during World War II, and loved for maintaining today lively presence at countless public events.

Her warmth, ease and broad smile are matched in the royal family only by her favorite grandson, Prince Charles, the heir to the throne.

Her birthday is actually Aug. 4, which she will celebrate in relative privacy. But today was her national birthday celebration, with the queen giving her mother the sovereign's pride of place at the head of the royal family throughout the day's glittering events.

Hundreds of thousands of Britons and tourists, many cheering and waving small Union Jacks, lined the two-mile route between Buckingham Palace and St. Paul's Cathedral for the queen mother's royal procession to a thanksgiving service in her honor conducted by the Archbishop of Canterbury.

The queen mother, in a light blue and lilac dress and summer hat, rode in a gold-encrusted horse-drawn carriage with Prince Charles at her side. The long procession included three other coaches carrying the queen and the rest of the royal family, plus hundreds of accompanying Horse Guards trimmed in scarlet, gold and flashing steel atop prancing black steeds.

A gathering of 3,000 people at St. Paul's, including Prime Minister Margaret Thatcher, heard the Archbishop of Canterbury, Robert runcie, say that the queen mother had made everyone in Britain feel part of one family.

"Royalty puts a human face on the operations of government and provides images in which the people of a nation can identify and which they can love," Runcie said from the raised pulpit. "What we have seen in one so greatly love and universally admired lady is a love which has been given by her to us, returned to her by us, and given out again by her over and over and over and over."

Britain's royal family, the most expensively maintained in the world today, costs the nation an estimated $35 million a year, plus what the monarch contributes from her own vast tax-free wealth. But aside from occasional loud grumblings from the political left, Britons seem to like what they and the tourists who come here get for the money -- the pageantry, royal palaces and parks, and frequent personal appearances.

The queen mother, affectionately known as "Queen Mum," is a short, plump, jolly woman, who personifies this personal side of the royal family.

With the somber hyperbole that one old British institution, the British Broadcasting Co., reserves for another, the royal family, the television narrator ended today's live BBC coverage of the queen mother's birthday celebration by calling her "a figure of hope and relief in a world of doom."

After her return to the palace today at the head of the procession, the queen mother made three appearances on the palace balcony with her two daughters, the queen and Princess Margaret, her son-in-law Prince Phillip, and her six grandchildren. With her famous smile and a wave, she acknowledged the spontaneous singing of "Happy Birthday" and "For She's a Jolly Good Fellow" from the crowd below.

Born Lady Elizabeth Bowes-Lyon, the youngest daughter of a not particularly notable Scottish nobleman, she made her first appearance to cheering crowds on the Buckingham Palace balcony in 1923 in her wedding dress after marrying then Prince Albert, the Duke of York.

She was back on the balcony wearing a queen's crown as she accompanied her husband on the day he was crowned King, following the abdication of Edward VIII, who married American divorcee Wallis Simpson and became the Duke of Windsor.

After her husband died and her daughter took the throne in 1952, she devoted herself to charitable causes, public ceremonies and the steeplechase horses she owned.