The Preston service can't have lasted long?
I think it lasted into LM days - I'm near sure it featured on the above door maps.
I'm not 100% on these odd workings though. But in terms of the general service:
Pre WCRM there were 2tph (I think) Euston-Brum semifast. These, unlike now, didn't call at local stations north of Rugby during the day, though may have done at less busy times (I didn't use them often).
During WCRM (West Coast Route Modernisation) the service was split at Northampton, with only 1tph of Central Trains service from Northampton to Birmingham. I seem to recall though that some trains actually operated through on an unadvertised basis later on in that period, with a CT crew taking over from the Silverlink crew (and vice versa) at Northampton. This wasn't all trains though. Where it actually was separate this might have been the most reliable time for the south WCML as it was mostly self contained.
The Southern service pre WCRM went Rugby-Gatwick, during WCRM it was cut back to Watford, then quite a lot later it extended to MKC in place of one of the Euston stoppers. It is of course now back at Watford again. I'm less familiar with what happened at the bottom end as I've only ever really used it to Clapham and occasionally East Croydon.
With regard to the Crewe service, this was since BR days a 153 (or sometimes a 150 I guess as others have reported that) on a purely local service. The through service was a brainchild of London Midland whose franchise required them to operate a local service, but they decided to run it through to Euston as pseudo open access, which proved extremely successful. I don't recall the initial north of Northampton only workings, but the start of the hourly service post WCRM was in the form of an hourly 8 car which ran fast to MKC and Northampton, where it split to go to Birmingham and Crewe. I seem to recall Platform 5 at MKC was its main haunt once this was in place (it may even have been required to start it, I forget exact dates). Obviously this fairly quickly proved inadequate for demand which led to the later 8 and now 10/12 car workings and the separate Birminghams.
In latter LM days there were three through Birmingham-Euston services, two linked to fasts (Leighton and Euston) and one to a semifast (everything bar Cheddington, Apsley, Kings Langley and Bushey I think), this one was overtaken but was still part of the advertising, and was useful for Bletchley passengers.
I can't remember the situation with the local services before Tring got its reversing platform - I think they worked through to Bletchley? But I lived nearer MKC then so didn't really use Bletchley. In the days when the Virgin service was just one of each per hour plus a second Birmingham and Chester a few times a day there were possibly more fast line Silverlink services? I know there were in the peaks nonstop MKC-Euston Silverlink services, certainly, the loss of which (in favour of the Leighton Buzzard stop) was very controversial locally.
