Louis Armstrong's secret daughter revealed, 42 years after his death

He was the Father of Jazz, a notorious womaniser who married four times, but Louis Armstrong was thought to have died childless.

Now, 42 years after his death, letters written to a former mistress by the genre-defining trumpeter and singer have emerged, revealing how the man known to fans as Satchmo or Pops kept a secret second family.

Sharon Preston-Folta, 57, a marketing worker with more than a passing likeness to Armstrong, has stepped forward for the first time to claim that she is his daughter, producing nine letters and other correspondence in which he professed his love for her even before she was born.

"I chose to tell my story now because it's about my legacy," Ms Preston-Folta said as the correspondence went up for sale at auction this weekend. Experts have ruled the documents authentic.

"I matter. My story is important. I have every right to say who I am, to be proud of it. It was never a secret to me who my father was," she told the New York Times.

Armstrong was noted by several biographers as having never fathered a child, though he did adopt his late cousin's mentally disabled son, Clarence, at the age of three. His fourth wife, Lucille, signed an affidavit for a probate court following Armstrong's death in 1971, stating that he had no biological children.

Yet for 16 years, he had supported Sharon and her mother, acknowledging the child as his and buying them a house in New York state where he would visit them.

"After Louis was gone, because my mother didn't step up and insist that I be recognised, the estate didn't have to. My mother has a saying, 'Those that know know, and those that don't know don't need to'. She felt that I was recognised in his eyes." Ms Preston-Folta told a newspaper in Armstrong's hometown of New Orleans.

Her mother is Lucille "Sweets" Preston, a former dancer at the Cotton Club in New York, with whom Armstrong began an affair in the 1950s.

In November 1955, Miss Preston told Armstrong that she was pregnant with his child. Writing to her while on tour, Armstrong referred to their forthcoming arrival as "my little Satchmo" and declared himself "so proud".

"You must remember, I never had a baby before," he wrote, telling her in a later letter that he hoped to one day leave his wife, Lucille. "If I ever get rid of that evil selfish Bitch, whether you want me or not you will have to marry me. I prey (sic) to God every day for that moment," he wrote, signing off as "Your future husband".

He never did leave his wife, who later dismissed claims that the baby was his, claiming that he was not capable of fathering children.

But Armstrong continued to see Miss Preston and fund her and her daughter. A letter to her in 1965, in which he referred to himself as the girl's "Daddy Satchmo", told of his promise to continue to support her financially.

"Whatever college she wishes to go to I've got her covered. All she have to do is finish high school and that's where I step in. As long as Ol' Satchmo lives, her happiness is assured. P.S. If I die, she will be straight just the same," Armstrong wrote.

Ms Preston-Folta, of Sarasota, Florida, claimed that her parents' affair had ended in 1967, when she heard them arguing in a hotel in New Jersey, after her mother demanded to know when they would be getting married.

"Hearing him say 'Never' was devastating," she told The New York Times, though the couple made up six weeks later. The following year, Armstrong wrote to her mother: "Sharon may not realise now what I mean to her and [am] doing for her.

"But I am sure as she matures she will dig Pops as the man who'll be loving her until the day he dies or she dies. That's sincerity and from the heart."