Born in London, Cogan's chart career ran from 1954 to 1961 as she sang innumerable hits on the cusp of the rock era.
Dubbed "The Girl With A Giggle In Her Voice", she was the highest paid British female entertainer of her era.
Alma's mother encouraged her to enter show business, and she auditioned for Ted Heath as a child. But her real patron was an executive of HMV Records, Walter Ridley, who saw her potential as a teenage art school student.
Her first record was a 78 rpm record of To Be Worthy Of You on HMV. When Joy Nichols left the BBC programme Take It From Here, Cogan replaced her as the resident singer, performing many types of songs but, most successfully, up-beat ballads and novelty songs.
In 1953 she was working on the song If I Had A Golden Umbrella and broke into a giggle while recording it. The people decided that they liked the sound, and that sound became her trademark style. In 1954 she had her first chart hit, a cover of Teresa Brewer's Bell Bottom Blues.
She had many UK chart hits, some of which were covers of US hits, including some Rock & Roll flavoured ones as the 1950s progressed. Her recordings for EMI were produced by Walter "Wally" Ridley and then later by Norman Newell, with whom she had some disagreement.
In 1965 EMI Records decided that they would not renew her contract with the company and requested that their newly hired young producer, David Gooch, produce an album of material which would bring the association to a conclusion.
Cogan had wanted to make an entire album of Beatles material, but EMI felt that that was unsuitable since there were a number of other similar recordings available at the time.
Cogan died in London in 1966 from ovarian cancer at the criminal age of 34. She is commemorated by a blue plaque on her former residence in Kensington High Street.
For many years there were rumours that Alma had been involved in an affair with John Lennon. Cynthia Lennon became convinced that Alma and John were lovers. "I could see the sexual tension between them," she recalled, "and how outrageously she flirted with him. But I had no real grounds for suspicion . . . just a strong gut feeling."
It was revealed after Cogan's death (by her sister, Sandra) that Cynthia's suspicions were correct. Alma and Lennon, both heavily disguised, took to meeting for passionate interludes in anonymous West End hotel suites, where they sometimes registered as 'Mr and Mrs Winston' (Lennon's middle name).
"John was potty about her," George Harrison revealed later. "He thought her really sexy and was gutted when she died".