Shakespears Sister’s Stay is still the longest-running No.1 song by a female group. But it also drove a wedge between Siobhan Fahey and Marcella Detroit. The reunited pair remember writing the song that would make them – and break them…

Siobhan Fahey: We’d written about five songs for the Hormonally Yours album. Dave [Stewart, of The Eurythmics and Fahey’s then-husband] dropped me off at Marcy’s to start work one morning and he came in for a minute. He said, “Why ...