The first summer Sunday service starts at Shrewsbury.
I know that - but it simply replaces a later morning service from Shrewsbury. It's not an extra train.
Look at the service patterns.
Westbound, the winter pattern is
From Machynlleth - 08:50, 10:50
From Shrewsbury - 11:27, 13:27, 15:27, 17:27, 19:27 and 21:30
The summer pattern is:
From Machynlleth - 08:50, 10:50, 12:35
From Shrewsbury - 08:45, 13:27, 15:27, 17:27, 19:27 and 21:30
Eastbound, the winter and summer patterns are identical.
From Aberystwyth to Shrewsbury: 09:30, 11:30, 13:30, 15:30, 17:30, 19:30
From Aberystwyth to Machynlleth: 21:30, 23:30
What happens in the summer is that the 11:27 is advanced to 08:45, and then it is joined by an extra unit at Aberystwyth.
Hence my question above as to how best that the additional units could be used on Sundays.