The York-Shrewsbury mail is covered in detail by Express Publishing’s ‘Operation West Coast’, the following is a direct extract regarding the southbound working in 1955;
23.58 Stalybridge - Stockport - Crewe - Shrewsbury - Swansea (08.06)
This service was actually the South Wales section of the 21.50 York - Liverpool which divided at Stalybridge and was unaccountably - since nothing about the service had any connection with North Wales - known throughout the system as the ‘Bangor Mail’. As the West Coast Postal connected the LMS system from North to South, so the Bangor Mail connected the system from North East to South West with the common meeting ground of Crewe.
The heart of the train was the three-coach section (plus a Full Brake) which worked through from York to Swansea but there were a number of vehicles which ran with the service for short periods. Of these, the most prominent were the pair of TPO sorting vehicles that ran from York to Shrewsbury and were accompanied by a Full Brake which came from Newcastle and contained mail from the North East to be sorted and bagged in time to connect with the other mail services at Crewe. More mail was attached at Stockport, some for Swansea and some for Aberystwyth via Whitchurch. The rear of the train was brought up by a pair of fish vans; one, from Grimsby, acquired at Stockport and the other from Fleetwood and attached at Crewe. The Grimsby vehicle ran to a very tight schedule since it came into the area in the 17.15 Grimsby - Guide Bridge via Woodhead and was then tripped to Manchester London Road to be attached to the 00.10 London Road - Stockport parcels. The passenger coaches and TPO vehicles remained in Swansea and Shrewsbury respectively until forming the corresponding service the following night.
The BR version of the train differed very little from that of the LMS era, the main change being that only two passenger coaches ran through from York to Swansea although a third vehicle - an LNER brake composite - was conveyed from York to Shrewsbury.
Incidentally - to give a sense of the size and complexity of the southbound working - the formation of the train between Crewe and Whitchurch was 13 vehicles, 7 of which had originated in the 21.50 ex-York.
The northbound train in 1955 was a much simpler affair and the book has the following to say:
18.30 Swansea - Builth Road - Shrewsbury - Crewe - Stockport - York (03.37)
Named, for no obvious reason, the Bangor Mail, the 18.30 Swansea - York was the only Central Wales passenger service to run beyond Shrewsbury although the greater part of its importance came from the Royal Mail vehicles that worked between Shrewsbury and York. Worked by a Shrewsbury 5MT 4-6-0 to Stockport and a Longsight 5XP 4-6-0 beyond, the train did not combine with the Liverpool - York Mail as it did in the opposite direction but ran through to York as a separate working. The engine was that which later piloted the 09.50 Newcastle - Liverpool Express between Leeds and Manchester; finishing its day as pilot to the 21.50 York - Swansea which it worked between Stalybridge and Stockport.
The train had changed very little over the years and the only difference was that before the war two instead of three passenger coaches had been worked from Swansea although to compensate, an LNER brake composite had been added at Shrewsbury and went not only to York, but was transferred to a North Eastern train and taken through to Newcastle.
Again, for reference, between Shrewsbury and Crewe the formation was 8 vehicles, including 3 passenger coaches.
Hope this is of interest, I really recommend the Express Publishing series of books If you’re interested in timetabling and rolling stock diagrams / train formations in steam age.
