The mother of Britain's Queen Elizabeth appeared before thousands outside Clarence House ina steely show of determination. The country's oldest royal had undergone an emergencyblood transfusion for anemiaon Wednesday.

She wason her feetfor nearly 15 minutes as shetook the salute ofthe Scots Guards marching with the band of the Grenadier Guards playing "Happy Birthday".

The Queen Mother also stood to receive bouquets and greetings cards and to greet a number of children.

She then greeted the crowds for three quarters of an hour from her chauffeur-driven golf cart, nicknamed the "Queen Mum Mobile".

"I'm feeling much better," she told people as theybroke into a chorusof "Happy Birthday to you."

Her 100th birthday last year, when she became the royal family's firstcentenarian, was marked with lavish celebrations and an outpouring of affection from her admirers.

A crowd of 40,000 people surged towards the gates ofBuckingham Palaceto applaud Britain's best-loved royal.

In 70 years of service, the "Queen Mum" has remained a popular figure while other royalsfell in and out of favour.

After herself-effacinghusband unexpectedlytook the thronein 1936, replacing his brother who had abdicated, she worked tirelessly touphold the royal family's reputation and popularityas the old order and class barriers crumbled.

She became a key focus formoraleduring World War Two, defying German bombers by staying in London through the Blitz. Adolf Hitler described her as the most dangerous woman in Europe for her effect on public spirits.

A newspaper quoted unnamed royal sources earlier this week as saying the Queen Mother had told house guests at the Sandringham royal estate in eastern England that she wanted to become the country's oldest woman.

Amy Hulmes, aged 113, is believed to be Britain's oldest living woman.