Further thoughts somewhat on the wild side on this threads general theme. Blame my fondness for Colonel Stephenss standard-gauge light railways; and my recent receiving of the Colonel Stephens Societys quarterly magazine. As well as the recently-discussed Swansea & Mumbles; Britain had another standard-gauge oddity with the same initials Stephenss Shropshire & Montgomeryshire Railway. The above Societys magazine (called The Colonel what else?) includes in its latest issue, a brief article about said Col.s S & M, in the 1930s.
Survival-wise, the Shropshire & Montgomeryshire was luckier than a couple of Stephenss lines, in being taken over in its then freight-only moribund state, by the Army in 1940 (plans, which were implemented, for big military installations / ammunition depots in the remote countryside unlikely for targeting by enemy air action served by the line). The S & M (main line Shrewsbury [Abbey] Llanymynech, plus the branch Kinnerley Criggion) served the Army not only until 1945; but remained in Army use (plus civilian freight traffic) until abandonment in 1960.
Given the approximate date parameters suggested in my OP: it has occurred to me, what fun it might have been for a preservation society to have been able to inherit the S & M from the Army. My criterion of going somewhere meaningful: lines eastern end, Shrewsbury (Abbey) station near the heart of Shrewsbury city with the line running essentially north-westward therefrom, to serve the local outback (no offence intended), linking same to the county town. Physical connection with the national network at Meole Brace, a little way west of Shrewsbury on the Welshpool line.
Various possibilities, as regards western terminus under preservation. Kinnerley Junction, the lines nerve-centre, thirteen and a half miles from Shrewsbury; and the Kinnerley Criggion branch, six or seven miles long. The line as a preservation venture: perhaps, Shrewsbury Kinnerley Criggion: roughly twenty miles; as preserved lines go, long but not unheard-of. South Shropshire is hilly and beautiful; the countys more northerly parts, as between Shrewsbury and Kinnerley, are bucolically pleasant, but low-lying and unexciting. The far end of the Criggion branch gets into agreeably hilly country a trippers-pleasing end to the run?
Or some five miles on along the main line: Kinnerley Llanymynech; the latter station was still on passenger routes in 1960: but one would not, even then, have needed to be Nostradamus; to envisage a likelihood in some not far distant time, of the closure of such highly-rural and routeing-avoidable sections. Remote and far-out possibilities perhaps, concerning the Nantmawr ballast quarry on the one-time complex of lines west of Llanymynech (quarry rail-served in real life, long after 1964s passenger closures) and cutting of deals between British Railways and the preserved line, re serving of same plus S & M passenger to Llanymynech, the latter still kind-of counting as somewhere: rather a feeling, though, that this way, madness lies. At all events Ive always liked the S & M, and would have loved to see it worthwhile-ly preserved.