It’s a shame one can’t make a free enquiry at the Land Registry to find out. It would make a lot of sense if the land really was railway-owned, even if it was owned purely on a speculative basis.
Agreed, however from my day job I would imagine that tracking down conveyances from the 1890s for now-demolished houses wouldn't be something to be taken on lightly!
Trying to put some chronological order to it, we get the following:
1890s: St Paul's station opened and Vickerman Street developed. The long term plan seems to have been for St Paul's to become an intermediate station joining the S&C at Keighley with the Woollen district, Sheffield and London, which never materialised.
1927: Photo from ground level shows possibly two or three screens in place but no more.
1930s: Aerial photography shows 6-8 structures in place, but not at every house.
I wonder whether perhaps Vickerman Street was developed as a source of rental income for the railway until the through line was built and the whole site was needed. By the 1920s it would have been clear that this wasn't going to happen, particularly after passenger services were withdrawn in 1917. However, if the houses were built in the 1890s, wouldn't they have already acquired the rights to light by 1931? Perhaps once the grand scheme for the through line failed, the railway cut its losses and sold the houses on.
Looking at the station plot and the alignment of the track, it's difficult to see what operational use could have been made of that part of the land, except possibly a warehouse or goods shed on a kickback siding, and there's a half length street (Aspinall Street) between Vickerman Street and the railway land which might have served for access.