It could well be. "A Pictorial Survey of London Midland Signalling" (D Allen and C J Woolstenholmes, OPC, 1996) has it in Plate 198. It is a Midland box and has the right number of sections etc. But the external walkway in front of the windows has been removed, by Robert Humm, I presume (they moved the box and rebuilt it, according to the photo caption.)
The only error on the Hornby model is the staircase coming straight from the door. It was standard practice to off-set the stairs from the door (at least on Midland boxes), I assume to stop a headlong fall down the stairs if the signaller should trip on the door threshold. It was also the practice to site the stairs so that the signaller came down facing approaching traffic. I have to say that the stairs seem a bit steep as well.
Now, can I cut up two models to make a 3-panel box like St. Albans South, I wonder? (As I'm helping to restore that!)
Regards,
John Webb