For the complete picture for the benfit of some younger members who may not know, perhaps you should also post the West of England to Manchester and Liverpool service that operated via Maindee East, Herefore and Shrewsbury in those days.
Although I understand what the point of this thread is, it might give the impression that there were no through trains back then to and from the north west.
The west to north-west services had already been diverted via Birmingham shortly after 1971. If I recall correctly they ran via Worcester and were overtaken by a Cardiff - north-east service, giving connection between the two routes at Cheltenham or Birmingham