From this morning's log:

06:44 train on 24/09/2007 shows as 07:18

and to be fair it was a brutal morning with various trees down and it must have been very tempting for FGW to cancel some trains.  They didn't ... and although it's missing from the log, research tells me that the 07:17 left at about 07:32.  Notable that they expect it to be within 2 minutes of time when it gets to Cheltenham - after being 16 late off Westbury.    That's a generous recovery allowance somewhere