After playing around with various old maps, planning portal and some aerial photos I seem to have established that the area I want to model be approx 2.7m long to scale. This takes in the area from Sun Street bridge to the south facing wall of the main station building. I'm considering whether it might be necessary to trim this down closer to 2.4m by reducing the gap between the bridge and the end of the station buildings. The big concern however is the width of the layout. To fit this in to scale will require a board depth of around 1.2m some four times the depth of my Foundry Lane plank! It may be possible to reduce this slightly, by reducing the depth of the buildings and platforms a little. I've sketched the layout of the station building and have approximate dimensions.

Unfortunately, I've had to omit one building (a single store red brick building which stood between the main building and the bridge adjacent to the bay platform) from the plan. Main reason for leaving this out is that it would block the view of the platforms as viewing (and operating) side will be from the front aspect of the buildings.

Current plan is as follows -

What I aim to achieve is a layout where most of the stock spends most of its time on the scenic area rather than hidden away in the fiddle yard. So, as shown in photos from the period, there will be vans awaiting loading/unloading on every available bit of track. The bubble car was often stabled in the middle road between its peak-hour-only trips to Snow Hill.

There is a comment in "Mainline to Metro" (John Boynton, Mid England Books) to say that the final train from Snow Hill (1972) was unable to run to Low Level as track rationalisation meant it would not be able to run round. A caption in "Diesels in the West Midlands & Central Wales" (Bradford Barton) states that by 1974 connection to the mainline had been severed and only access was via the Midland line at Heath Town junction. Therefore I'm assuming that all parcels trains would have been propelled into the station - unless there was a 08 on pilot duties to release the train loco from inbound trains?