The Midland Mainline runs between London St Pancras and Sheffield. For many years, the main motive power was Class 45/46's with 47's and 31's occasionally covering for the 'Peaks' when they are unavailable. This route would cover the section between London St Pancras and Kettering during the era of semaphores and pre-electrification. Stock Class 45 Class 47 Class 117
Well there ain’t many Peak Variations, a Split head code 45 would do, I would also replace the 117 with 127s, unless you meant 127s, idk the picture for it ain’t loading and it says 117, probably also Remove the 47 could just be a Layer, but all that is up to you. Nothing much else I don’t want to accidentally rehash my own Midland Mainline suggestion here.
The Class 127 was indeed the correct dmu on this line and were known as Bedpan units (Bedford to St Pancras). These dmus were diesel hydraulic and operated slightly differently than the Class 101 we already have.
The Peak era, along with the 127s on the suburban services, would be great. Happy memories of my youth cycling from Northampton to Wellingborough to indulge an hour or two of watching the 45’s screaming past.
I believe there is a 127 in Diesel Railcar Simulator. It is easier to drive! Also don’t forget the penchant for drivers to keep the blinds firmly down between the cab and saloon to avoid nosy stockbroker types or HQ railway managers eyeballing the speedo.