Singer was surprised to be introduced to his girlfriend!
The singer, 23, worked with the producer on her debut album Alright, Still in 2006.
And Lily immediately jumped to the wrong conclusion.
‘I met Mark at a club night in London called YOYO,’ she tells Paper.
‘I thought he was cute, but assumed he was gay. I remember being shocked when I was introduced to his girlfriend at the time.’
Lily collaborates with Mark, 33, on her new album It’s Not Me it’s You, to be released in February.
He recently split with model Daisy Lowe, 19.