The Dunstable branch lines were a pair of branch lines operated as one in their later BR years that ran between Leighton Buzzard where it connected to the WCML, via Stanbridgeford, Dunstable, Luton and Welwyn to the ECML until the line was closed in 1962 from Leighton to Dunstable and 1965 from Dunstable to Welwyn/Hatfield. It would have been my local line if it had continued to exist, and I would love to see it brought to life in TSW 3 so I and others could in some capacity experience the line as it would have been, ideally in its later BR years like 1955-60ish.
Nice call. Fairly certain this is the route that crossed under the Midland Main Line at Chiltern Green, subject of a famous 2mm scale model railway some years ago.