The Morris Cowley trains generated several reports in Modern Railways 'Motive Power Miscellany' section in the early 1960s. Here's a few examples
March 1963, LMR - The named Class 9 2-10-0, No. 92220, now stationed at Oxlord, is frequently employed on the 1.50 pm Morris Cowley - North Mersey Class 4 freight and return working fron Aintree Sorting Sidings.
November 1963, LMR - The substantial stud of "Britannia" Pacifics at Crewe now have a rostered working to Oxford on the twice weekly 3.30pm Bathgate to Morris Cowley.....This service was established some time ago between Morris Cowley and destinations in the Liverpool area, but recently it has been reorganised and retimed on a much faster schedule, being simultaneously upgraded to Class 3. Previously it was hauled by Class 9F 2-10-0s.
Reports from the WR late 1963 / early 1964 would suggest that the Brits did a few fill-in turns from Oxford to Swindon.
April 1964, LMR - Brush Type 4 diesels have also replaced "Britannia" Pacifics on the 13.14 (MWFO) Morris Cowley to Bathgate and the 12.00 TThSO) return car carrying trains, although it is not clear whether the diesel locomotives (nominally WR units) are working north of Crewe on these turns.