No need, there are a few examples shown in Modern Locomotives Illustrated for the Class 80 to Class 85 for anybody that has it. One of the 85s even hauling a Glasgow to Euston pictured at Crewe with Mk1 Mk2 and Mk3 stock in tow. They hauled Mk3s alright that much weve established.
I wish I could go along with the suggestion made about the Liver/Manchester "splitters" via Preston as these were rarely if ever made up of Mk3 stock having travelled many a time on these trains north and southbound in the late 70s to mid- 80s. They were largely a mix of the early Mk2 and then later Mk2e/f plus your BG or what have you Mk1. Ive certainly never seen or heard of any Mk3 rakes getting joined or split either at Preston during the period mentioned. Mk3s may well have been split at Carstairs but not on services to Liver/Man.
The 85 does stand a good chance of having just brought the stock in from Edge Hill CS as empties but that alone doesnt explain the conundrum that is, why is 1st is at the Liverpool Lime Street end.........the mystery rattles on and so do the speculations!