Life really did begin at 40 for businessman Jack Pearce. He was about to embark on his first trip to Florida, with his wife Jane, when his mum announced the bombshell news that the man he believed to be his dad was in fact his step-father.

And his true dad was one of the greatest singers of the 1940s and 1950s and a multi-millionaire. He was Billy Daniels, whose hit That Old Black Magic in 1948 sold 12 million copies and made him a household name.

So for the past four years Jack, 46, who lives at Haworth and runs Euro Shopfitters in Bradford, has been compiling information and writing a biography about Billy.

Not only has he found his true father, but discovered he has five half-brothers and sisters - his father, who died 12 years ago - had married three times. Jack said: "His friendships encompassed everyone from Martin Luther King and Nol Coward to Tom Jones, who helped carry his coffin into church in 1988.

"I discovered that my father was the first black man to host a television show in America. He appeared in eight Royal Variety performances and six Hollywood films. I felt an overwhelming loss that I had never had a chance to get to know such a remarkable man."

But now Jack is making up for it and keeps in regular contact with his fascinating family. There is lawyer Bill, Diane, a retired opera singer, both in their late 50s, and Bruce, in prison for life for drugs offences - all children to Billy's first wife who died in childbirth.

And then there is Andrea, 42, and Domi, 40, the children from Billy's third widow, Periette. He separated from his second wife.

Billy met Jack's mum Audrey Cock-croft when she was making a career as a singer in London's West End, using her showbiz name of Rae Croft. She was 21, he was 36 and their love affair lasted three years. Jack was born in June 1954 in Brighton, and Billy spent a week with them. "It was our only time together as a family before he left for a tour of Australia and then America to make a film. He wrote regularly to mum and sent money," said Jack..

"We moved back up north. Nan raised me while mum worked as a telephonist during the day and collected insurance premiums in the evening. She gave up any ambition of a singing career to devote herself to me." Billy and Audrey met only once more, in London when he was appearing at the Palladium during his 1955 tour, when she learned he was seeing another women, Periette.

Audrey went on to marry Freddie Pearce when Jack was six years-old and they lived in Barnoldswick, Jack eventually studying at Bradford art college, later gaining a degree in interior design.

Jack has visited his family in the USA and talks to Periette every two weeks and exchange e-mails. He corresponds with his other half-brothers and sisters, including Bruce in prison. "My great regret is not discovering the truth about my father while he was alive, but I have no complaints. My life has been good.

"Before Billy died of stomach cancer 12 years ago, he made a tape asking Periette to find someone to write his life story.

"When I heard the tape I knew I had to do it. It will be my gift for my father," said Jack.