A Baffling question on the soundtrack

To answer this, you need to be familiar with the [original] 1973 film 'The Wicker Man'. Regarding the song which Willow (Britt Ekland) sang in that film, when she tried to entice Sergeant Howie (Edward Woodward) into her room at night; a re-make of this song was playing in 'This Life', at the flat. I never knew, until last year when I played the complete Series 1 & 2, that this song had been done again. Does anyone know who it was buy? I'm about to play the CD soundtrack, which came with the new R2 Optimum three disc special edition of 'The Wicker Man' (1973).
I didn't note which episode of 'This Life' it played in, but it was about in the middle of the boxed set.