......amongst other cancellations due to crew shortage on the first weekend of the school summer holidays, this one particularly stands out........
11:37 London Paddington to Newquay due 16:42
11:37 London Paddington to Newquay due 16:42 will be cancelled.
This is due to a shortage of train crew.
The reliability of the Newquay and Paignton weekend trains has been appalling. Of that there is no argument.
However, there is logic behind cancelling that train instead of others.
The 12:04 Paddington to Penzance follows it until Par (where the Newquay branch splits off) arriving at 16:05, 9 minutes after the cancelled Newquay service would normally have left.
GWR▸ ran an additional 15:30 Plymouth to Newquay service scheduled to depart Par at 16:14 arriving Newquay at 17:00, instead of the original train at 16:42, so only an 18 minute 'delay' on the through journey. The 12:04 would have course have been a busy train in its own right, but was a 10-car - the longest that can operate, and it does miss out a couple of stops en-route (Westbury and Tiverton Parkway).
Now, not everything goes to plan. It turns out that the previous Paddington to Penzance train was delayed at Paddington and didn't leave until 11:38, and almost ran in the path of the cancelled 11:37. That too was a 10-car so would have helped spread the load of the 11:37 onto two trains rather than one. That was fortunate. The 12:04 ran behind it arriving Par 8 minutes late and that caused the additional train from Plymouth to leave Par 10 minutes late, and arrive Newquay 6 mins late so actually a 24 minute delay on the through journey. The additional train was a 2-car Class 150 so might have been quite full from Par as there were 111 reserved seats to Newquay on the original train (not all from Paddington), including 12 1st ones with no 1st class provided on the 150s.
Not a perfect solution, but perhaps a useful indication of why that particular train was cancelled?