The Three Degrees

They are the longest running female vocal group in music history beginning in 1963.
Known for songs like "When Will I See You Again", "Dirty Ol' Man", "TSOP- The Sound of Philadelphia" with MFSB on Philadelphia International Records and disco hits like "Giving Up Giving In", "The Runner", "My Simple Heart," and the lust ballad "Woman In Love" on Ariola Records produced by Giorgio Moroder. Their performance at the Copacabana in Manhattan ended up in the film The French Connection (1971).
The current members are Helen Scott, Valerie Holiday, and Freddie Pool.