THE Queen yesterday sent her mother a special 100th birthday greeting - and signed it ''Lilibet''.

The handwritten message inside the Queen Mother's Royal birthday card read: ''On your 100th Birthday all the family join with me in sending you our loving best wishes for this special day. Lilibet.''

Rather than signing with the formal ''Elizabeth R'', the Queen, 74, used the name her family have called her since childhood.

The Queen Mother's 100th birthday card - the Queen no longer sends telegrams and telemessages - was delivered by the Queen's postman.

Tony Nicholls handed the royal family's first centenarian the card at the main gates of Clarence House, the Queen Mother's London residence, just before noon.

''It's the highlight of my career,'' said Mr Nicholls, who has been a postman for 34 years and the Queen's personal postman for the past nine years.

''I feel it a special honour in being able to deliver the birthday card from the Queen to the Queen Mother,'' he said.

Mr Nicholls, 58, from south-west London, works for the Royal Mail but is based at Buckingham Palace in the Court Post Office.

His normal job is to deliver mail addressed to the Queen wherever she might be - at the Palace, at Windsor Castle, at Sandringham in Norfolk, or at Balmoral in Scotland.

The 100th birthday card, in an envelope with the Buckingham Palace crest, is similar to cards being delivered to 11 other centenarians all of whom share the Queen Mother's August 4 birthday.

Measuring six inches by eight inches and featuring an informal colour photograph of the Queen in a red dress, pearls and diamond brooch, the new-look card carries a greeting printed on an inlay beneath the royal coat of arms and secured by a gold tassel.

The standard message, signed Elizabeth R, reads: ''I send my warm congratulations and best wishes to you on celebrating your one hundredth birthday on 4th August, 2000. I hope you have a wonderful day.''

But the Queen decided to write a personalised 100th birthday wish to her mother.

The laser-printed cards were introduced last year, instead of telemessages which replaced telegrams in 1982.

The Queen Mother took the salute from the King's Troop Royal Horse Artillery riding past Clarence House.

The band of the Irish Guards then marched past playing Happy Birthday followed by a contingent of the Grenadier Guards.

The Queen Mother has been presented with a birthday tribute from her four-legged friends - a rendition of Happy Birthday by four corgis.

The 30-second tape features Laila, Zoe, George and Gina barking in time to the tune of Happy Birthday.

The foursome from Cirencester have been trained to bark on cue by their owner Maria Carter.

The Queen Mother yesterday became one of Britain's more than 8,000 centenarians.

The number of people reaching 100 has steadily increased in recent years.

In 1951, there were only 271, in 1971, the number had grown to 1,185 and in 1991, there were 4,400 centenarians.

By 2031, there are expected to be as many as 36,000.

Based on current trends, at least one person will reach the age of 116 every year by the 2080s.

A Jewish man whose mother who was imprisoned in a Nazi concentration camp during the Second World War yesterday thanked the Queen Mother for reuniting the pair.

Jacov Friedler, 71, wrote to the Queen Mother in 1946 when she was Queen after he found that his mother, Hennie, had survived the camp at Bergen-Belsen in northern Germany but had been denied entry into Britain.

His long letter, which pleaded with the Queen Mother to allow his mother to join him in Britain, prompted her to intervene. Mr Friedler, who was a 17-year-old refugee in London at the time, said: ''A few days later I got a letter from the Home Office saying that on the command of the Queen my mother's case had been reviewed and that she would be allowed into Britain.''

Mr Friedler, who now lives in Israel, wished the Queen Mother a traditional Jewish birthday greeting.

''May you live to 120 which is, of course, the age Moses died,'' said Mr Friedler.

His mother Hennie died in 1958.