G-VAST's last few movements:
On Monday it operated the VS75 (MAN-MCO) on time
Monday night it did the VS28 (MCO-LGW) took off 1.5 late and didn't make up time due to unfavourable weather
It was then mean to have 6 hours before operating VS93 (LGW-CUN) but it took off 4 hours late (so 10 hours sitting at LGW).
Last night it took off from CUN on VS94 4.5 hours late and is due to land at LGW at 1415 this afternoon.
VS15 due to go at 1310 so it'll be as soon as they can turn the jet around, at least 1600.
It looks like something went tech during the LGW layover, maybe some planned maintenance ran over and it's been playing catch up ever since.