No again Gareth. Nothing to do with the 13 09. What I'm imagining could be 6 Cars on 07 30 Aber (2 ex Aber, 2 ex Barmouth 2 ex Salop off 06 30 ex Aber.
Return working 11 09 ex Intl to Holyhead, 15 33 Holyhead to Intl then 20 09 Intl to Aberystwyth. The idea in my mind is formed due to the unit 06 30 ex Aber shunts at Shrewsbury to attach to the 07 30 ex Aber.
I might be wrong as this is only a thought.
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Forget my previous posts, I can't surmise at least until the Platforming at Shrewsbury has been finalised. As it stands at the moment, the 07 21 Cardiff to Holyhead will "collide with" the 07 30 Aberystwyth to Birmingham Intl in Platform 4. The key may well be the set off the 06 30 from Aberystwyth shown to shunt to 4 and which also gets in the way of other trains !!!