Have a look at the "Shortage of train crews" thread in "Across the West".
Link at
http://www.firstgreatwestern.info/coffeeshop/index.php?topic=18719.1185 ... a thread that Taplow Green himself started and now has nearly 1200 replies!
After cycling 10 miles to Chippenham to get the train back to Bristol, I was dismayed to find all trains cancelled! Another 26 miles to get home riding against the sunset, just made it getting dark. What happened? Crew shortage?
Sadly, a classic illustration of the effect of this ongoing issue on just one person. Multiply that up by the number of passengers who would normally take such a train.