Versatile singer straddled jazz, classical, pop and musical theatre with four-octave range, and collaborated for decades with husband, John Dankworth

Versatile singer straddled jazz, classical, pop and musical theatre with four-octave range, and collaborated for decades with husband, John Dankworth

Her marriage to John Dankworth, the clarinettist, saxophonist and band leader, was one of the most successful partnerships in music history