Interesting. Could you elaborate on that and perhaps explain what could have been different prior to C19? Thanks.
It started off in 1840 as a single-platform station on a loop off the main lines. Very roughly, when you're in the middle of platform 2 you're round about the middle of that original platform and if you face towards 3, then the main building was behind you, accessed from Campbell Street (the stone gate-posts are still there).
A separate up platform was added in 1858, a few months after the Midland started through running to and from King's Cross over the Leicester & Hitchin line opened the year before. It was probably at the same time that a pair of goods lines past the station on the east side were also brought into use. This platform served the up main line.
A third platform, known as the excursion platform, was brought into use in 1868, and this was made by turning the 1858 up platform into an island. The big changes came in the 1890s with the building of the new station, fronting on to London Road, and the provision of the new goods lines between Knighton and London Road Jn. Platform 2, which at some stage had ceased to be a loop and had been made the down main line, thus kinking the DML both south and north of the station and producing the very visible dog's leg you see when you stand on that platform and look north, was lengthened north and south, but otherwise stayed in use and in place, but this too was now turned into an island, with the new platform 1 opening in October 1892.
The up-side island was rebuilt wider, with platform 3 also being extended north and south and the new platform 4 into use in July 1893. The whole station was finished about January 1896. But the thing that really mucked up the alignment was the final bit of widening, between Welford Road Platform and London Road Jn.
Over this section it is the passenger lines that are the new pair, to the west of the existing main lines, which became the goods lines. Doing it this way but keeping the run in to the station platforms where it was meant that the passenger lines had to get back across by the width of two tracks to make their entry to the station, and it's this, done in the brick-walled cutting, that accounts for the very awkward approach from the south and the severe speed restriction that goes with it.
The big question is why the Midland chose to do the last widening that way. Maybe the answer is that by the 1890s burials in the municipal cemetery had already come up to the railway boundary and it was easier to deal with relatively cheap property on the west side than with the need for exhumation and reburial on the east.
But if the goods lines had continued from the new Knighton Tunnel on the east side, to link up with the existing goods lines at London Road (as had been proposed about a quarter of a century earlier, before burials so close to the railway), then what was basically a full-speed alignment for the passenger lines would have remained. (Apologies for length, despite trying to be concise.)