Thanks for the responses. I'm looking at my Route Coverage map and presumed there must be a service as it is the fastest way to Sheffield from London however it would waste a path by not calling at either Derby or Nottingham.
In the future, apart from engineering diversions, would EMT or it's successor want to have services as I'm alluding to in this thread?
I forget exactly, probably 10 or 12 years ago, there was one Sunday working ex St Pancras somewhere in the 17.00 - 18.00 slot which went via the Erewash to Sheffield. I don't think there was an equivalent on the up.
Many years ago - like c 1970 - they diverted the Master Cutler via the Erewash and it saved about 15 minutes versus the Derby route (It didn't stop at Derby - and I have no idea why they routed it that way in the first place.) . AFAIR, it's not much faster than via Derby right now due to PSRs, especially at Trent. Presumably any time saved (and passengers perhaps gained by the faster running to Sheffield/Chesterfield) is not worth the loss of Derby traffic.
If, but presumably it's a big if, the TOC could realiably fill trains without the need to stop at Derby, it could be worth introducing a regular service this way. Either that, and/or Alfreton needs to double in size, or get a university or something to make it a decent generator for London traffic. Then it could build a business case to take our the PSRs, or some of them.
Going via Nottingham means too big a time penalty due to reversal, except for a couple of peak business services. I have no idea how they load between Sheffield and Nottingham. Anyone know?