Without a posting of a Google map for clarification, I will only hazard a guess.
There appear to have been two junctions around Ashby (De-La-Zouch) in times past.
One was a Midland line on up to Chellaston, closed in 1955.
The other was part of the Burton & Ashby Light RW line closed in 1927.
My wild guess is that what you are looking at was part of the first one, the Midland Line.
This is because just north of Ashby there was a very short branch to something only referred to as "Works" north of town.
[Reference - The Railways of Great Britain - A Historical Atlas Volume 1 Second Edition.]
Maybe this remnant is somewhat retained.
Or I could be totally wrong. But just wanted to try to guess as a casual armchair Yank.