I know the question related to South West workings but as that has included Hull in some replies I guess London should as well. 81A Old Oak had an allocation for a while from new, D9521 - D9524 from late 1964 to about October 1965, when they moved to Bristol Bath Rd.
Crew training seems to have carried out on a train of vans between Acton - Paddington.
Although allocated to Old Oak Common, it would seem they only went there for major maintenance work. They were based at 81D Reading, and I do remember (even if only about seven years old) recall seeing one or two at Reading General.
There were three diagrams worked with a fourth spare to cover for maintenance.
One was a midday Reading - Newbury freight, afternoon return Newbury - Reading freight, then early evening Reading - Paddington parcels. Light to Southall, early morning Southall - Reading freight.
Another was following. Morning Light engine Reading - Newbury for trip workings as required to Aldermaston, Hungerford, Welford Park (remnant of Lambourne branch). Evening Newbury - Reading freight.
The third. Worked late evening light engine Reading - Didcot. Next morning worked Didcot - Sonning coal (have seen a photo somewhere of this working). Afternoon Reading - Wallingford, Evening Wallingford - Reading.
I suspect that some of these workings were Conditional rather than Mandatory.
I cannot find original documents, but I think a contemporary RCTS Railway Observer carried info presumably gleaned from the official publications. Modern Railways from 1965 gives similar information and mentions them working to Basingstoke (D9524 05/08/65 on a parcels working). D9521 worked a passenger, 17.00 Gloucester - Cheltenham vice steam 27/11/65.
Hopefully of some use!
Paul