I Didn't Know I Loved You
From SistersWiki.org - The Sisters Of Mercy Fan Wiki
Full correct title: I Didn't Know I Loved You ('Til I Saw You Rock & Roll)
Originally by Gary Glitter ...
Lyrics can be found here, for example:
http://www.songtexte.com/songtext/gary-glitter/i-didnt-know-i-love-you-till-i-saw-you-rock-and-roll-3c8c99f.html