Thanks to Dazzle on the PopJustice forums
Here's the link - watch the video for yourself.
http://www.youtube.com/watch?v=OYt6uomVQOw
She looks amazing as ever, and sounds brilliant. I can imagine how good the track will sound in the CD!!

Sophie's set list for the event was:1. Take Me Home
2. Catch You
3. Starlight - brand new song from the 4th album
4. Groovejet (If This Ain't Love)
5. Heartbreak (Make Me A Dancer)
6. Murder On The Dancefloor
EDIT - after watching the performance over 17 times on my computer, i've made up my mind. The song has an amazing chorus!! I'm in love with the middle 8. It sounds very Madonna-esque. And the song is almost 4 minutes! Fulfilling!!! Kudos to Richard X. It sounds like an upbeat ballad, but then again, most of Sophie's songs do. I think she's saying "we beloooooooooong to the starlight starlight starlight". The sound on the recording isn't very clear. I can't wait for an actual HQ recording. It should be aired on the telly soon (maybe tonight), keep your eyes peeled.
EDIT 2 - after watching it again, i think its going to be the New York City Lights of the 4th album. Can't think of a better comparison. Extremely radio friendly, quenches your thirst, gives you everything that you were looking for in the song....