Thanks Alec. To be honest I thought it was the gantry, although Vbox should set it automatically to the correct place - and it doesn't seem to have done so, being about half way between actual start/finish line and the gantry. The longer I use Vbox the more quirks I seem to find.
Was a very good day btw. Not easy given the lack of garages, but seemed to go well nonetheless. I tended to stay back in the paddock to mind the fort, so found it very amusing to see Simon Norris running back from the pit lane to his paddock slot to grab a nut and spanner and then run all the way back to his car in the pitlane. Full marks for effort!