When driving the 158 on the Midland Mainline, some signed speed limits indicate 110MPH for HSTs and 80MPH for all other stock... the HUD however does not replicate this, keeping the speed limit at 110MPH which isn't what the timetable expects and leads to odd results with timings, plus isn't very realistic. This effect of two speed limits has been correctly done on other routes, but is seemingly not here. Example service: 2K39 Matlock - Newark Castle... look out for speed boards and compare to HUD.
The HST limits apply to Class 158s as well. (page 28 and 29). https://sacuksprodnrdigital0001.blob.core.windows.net/sectional-appendix/Sectional Appendix full PDFs March 24/London North Eastern (NCS) Sectional Appendix March 2024.pdf I will agree - it is very confusing!