if you are wondering what ones are 4 car and 5 car i don't think they have specific diagrams to follow, however I think that services on the Reading and Southampton route are usually 4 cars and the Edinburgh-Plymouth usually 5 cars during the week, can anyone confirm this?
Although I can't confirm this, my moves book tends to suggest this. I have only had a 220 myself South of Exeter in one of 3 circumstances
a) It was not a weekday
b) If it was a train from Paignton
c) If it was actually 2x 220
Therefore, what you say about PLY - EDB during the week seems to ring true (although I did see 4-car 221141 on one of those diagrams the other day, to add a further spanner into the works)
Thanks for your replies, however what I mean is does anyone know what train runs what services?
So for example
one of them does 5S37 then 1S37 etc