BEFORE Diana Ross met Mowtown maestro Berry Gordy, she was but one quarter of the Primettes: a wannabe whose nasal warble sounded thin compared to her co-vocalists. However Gordy changed the name and promoted Diana to the forefront of the group.

He was attracted to her - a decade later, they had a child together. Moreover, Gordy knew there was money to be made by anyone who could limbo under America's race lines. Ross reversed Elivs Presley's formula;

she was a black woman whose soprano voice meant she sounded, if not entirely white, then not black enough to lose the white mainstream.

Gordy was a colour-blind capitalist, or as an associate is quoted as saying in J Randy Taraborelli's biography: "Anyone who knows Berry knows that there is no colour in his eyes but green, the colour of money."

Known initially within Motown as "the no-hit Supremes", that trio's drought finally broke when Gordy hooked them up with the Holland-Dozier-Holland songwriting team ('Where Did Our Love Go?'; 'Stop! In The Name Of Love'; 'Baby Love'). Despite her pop-icon reputation, Ross was only as good as her collaborators.

When H-D-H left Motown over a royalties dispute, the Supremes' hit-making record faltered (and what a record - from 1965 to 1966, the Supremes released nine singles, six of them US number ones, and seven albums). Not that fans admit as much.

Gordy spoiled Ross, particularly after they became lovers. During a Supremes interview, he insisted his discovery be called Miss Ross.

She kept up this tradition severely, to the extent that her employees took to calling her "Miss Ross-ToYou" behind her back. Her staff wasn't to speak to or make eye contact with her unless invited to.

Before visiting lawyers or agents she phoned ahead to make sure all employees were quarantined in their offices. In contrast to the crowd-embracing Ross seen on stage, the private Diana appears people-phobic. Taraborelli sees this as her inheritance from her distant, imperious father, Fred.

But Ross's truly interesting psychological relationship involves another father figure: Gordy.

Despite a long relationship, neither could commit to the other.

Yet when their romance ended, neither could truly let go; Gordy was, after all, still the boss of Ross's record company. He continued to meddle in her life - and she continued to let him.

One can only imagine what life was like for her first husband, Bob Silberstein. As with another famous Diana, there were three people in that marriage.

Silberstein had a magnificently snooty description: "She is totally dominated by a man who has never read a book in his life. I just can't stand it any more, to hear them calling Stevie Wonder a genius. Whatever happened to Freud?"

With the decline of her commercial fortunes in the mid 1980s, Ross's legendary willpower crumbled too, to the extent that cohorts were astonished to learn at the start of the century that she was in rehab for alcohol problems.

She threw a well-publicised tantrum after being frisked at Heathrow and was booked in Arizona for drink-driving. Then she recorded a duet with Westlife.

All of which Taraborelli records in detail - this is his second biography of Ross. Considering how private she is - she approached one publisher with a serious proposal to write an autobiography including no personal details - this excavation impresses through bulk alone. Yet one is disappointed; the biography may be "unauthorised" but Taraborelli ran Ross's fan club in his teens, and while he doesn't elide her diva moments he does soft-soap unacceptable behaviour.

Finally, a word on length: 500 pages on Mao or Oscar Wilde may be acceptable, but Diana Ross? A record collection without a Supremes greatest hits is a mealy thing; nobody's book shelves will suffer without this biography.