The musicians teamed up to duet on their single Loving You, and they play lovers in the video accompanying the song, sparking speculation they were more than just friends in real life.
Chisholm insists their relationship is purely platonic, but she has now revealed they did indulge in a steamy kiss before the cameras rolled so there would be no awkwardness on set.
During an appearance on U.K. Tv show Let's Do Christmas with Gino and Mel on Thursday (19Dec13), she said, "We did have a practice before the video. Matt insisted...! It was quite nerve-racking and quite embarrassing, but it was great that we did have a practice because it did break the ice."