You are totally missing what my point is Conner.
They will probably have a limited number of staff in a link who sign Penzance - and all of those may have jobs at the time in question. Besides, in order for the 0830 to run don't the crew have to go down on that 06xx to Penzance? If that doesn't run (remember, booking on time can be 15 to 30 mins, not enough time to call someone else to come in at very short notice) then obviously the 0830 can't run.
Ooops pressed post too soon.
It just goes to show the absurdity of the current way of running the railways. In
BR▸ days the spare link man at Penzance shed would have taken the train. But now the drivers all work for different
TOCs▸ and so aren't even trained to drive each others trains so even if there was a spare
FGW▸ driver they probably couldn't drive a
XC▸ voyager.
Further more the "bean counters" have decreed that spare links are not economic. It's cheaper to pay the cancellation fee.