Kathy Kirby. Photo: Getty Images
Her family said she died last night (19th May 2011) after a short illness.
The blonde bombshell - whose biggest and best-known hit was Secret Love - also represented the UK in the Eurovision Song Contest in 1965, coming second to Luxembourg.
When her chart days were behind her, she then appeared in a number of TV variety shows. But she went on to withdraw from the public eye.
A statement released on behalf of her family said the singer “died suddenly last night after a short illness”.
“She will be greatly missed by her family and her many friends who have stood loyal over the years.”
She is understood to have died in London.
Kirby - whose niece Sarah is married to Sir Mark Thatcher - was one of the biggest stars of her day.
She had two top tens and three others in the top 40, which helped her to land her own TV series.
Born in Ilford, Essex, her career was guided by bandleader Bert Ambrose who took her on the club circuit before agreeing a deal with Decca Records.
She appeared on the huge US TV programme The Ed Sullivan Show and was courted by Hollywood movie producers.
Speaking in 2009, Kirby claimed she had a fling with Bruce Forsyth which had a profound effect on her relationship with her manager Ambrose, who was also her lover. She said Ambrose was turning down work because he was scared she might leave him.
“I think I could have played romantic leads or light comedy roles in movies but my silly affair with Bruce had inadvertently brought it all to an end,” she recalled.
“I could feel frustrated and bitter but in the end I just put it down to experience. What else could I do?”
She married a former policeman in the 1970s but the relationship was short-lived.
Kirby, who lived in west London, made her last major public singing appearance in the early 1980s on a TV special.
Kirby was also noted for her theme to hit TV show Adam Adamant, and she went on to record a number of albums in the late 1960s under a new deal with EMI, although the hits had dried up.
Following Ambrose’s death in 1971, she struggled to find direction in her career.
She was made bankrupt and suffered from some health problems, although she made a brief comeback in 1981, spearheaded by a reworking of the Charles Aznavour song She - renamed He.
But the return to the spotlight was to be short-lived and she decided to retire in her early 40s.
“I’d worked solidly from the age of 16. But for the first time in my life I found I liked not working,” she said.