When I go to visit the girlfriend, who lives just outside Reading, or go to gigs in London, I catch the 09.15, they tend to run to time, until arrival at Exeter. From a usual 2 or 3 minutes late departure, it tends to lose time, between 5 and 10 minutes down by Taunton departure, I now expect to be at least 15 minutes down on arrival at Reading.
I usually catch the "14.29" back, I regard anything less than 10 minutes late as an ontime departure, if the 14.37 to Newbury leaves before us, we will lose time until it arrives in there and then continue to lose time all the way to Plymouth. I assume that the late departure from Pad, is that the crew have arrived late and need to have their required break, or the stock arrived late in Pad.
The 80*'s don't have the get up and go of the HST's, to recover time and with big brother watching, there's no opportunity for the driver to give it a bit of extra, here and there.