Miles upgrade at Twilight check-in?

Due to fly out to Las Vegas on Saturday, and have an upgradable PE ticket, and whilst the chances are small that there will be a G seat available in UC, I thought I might try on Friday night twilight check-in and see if they'd consider it.

Does anyone know if the G upgrades that can sometimes be bagged at "normal" check-in would be available the previous evening at Twilight check-in (assuming that there was G available of course). I only live 20 mins from LGW, so thought it might be worth the trouble of packing a little earlier and chancing my arm at twilight check-in ?| ?

Likely? Thoughts?

Cheers and thanks...

flightstats is showing no UC seats left

J/0 C/0 D/0 I/0 Z/0

flightstats is showing no UC seats left

J/0 C/0 D/0 I/0 Z/0

...however, that one minor hindrance aside, what I have been told more than once at twilight checkin is to come back and ask again in the morning, as it's only on the day of the flight that the 'anything is possible' rule applies. Mind you, you've at least got an upgradeable fare rather than me chancing my arm on getting PE from a discounted O bucket...