I can elaborate on two of the holding units;
TMP Ashford - Training Materiel Park at the Ordnance Support Unit, Rowcroft Barracks, Ashford, Kent
OSU Ashford - same location as above, might have been drawn from TMP for the use of OSU.
The TMP was akin to vehicle hire depot, when units needed extra vehicles for a scheme, or had some out of service they would draw what type they needed. Anything from a motorcycle, Land Rover to a 10 tonner or 14 tonner.