I was not aware that Reading was on the West Coast Main Line. A Reading to Manchester service would clearly join the West Coast system at Birmingham and then run on the electrified former L&NWR/NSR main line to its destination.
There are a number of lines the Reading to Manchester uses which clearly depicts it isn't part of the WCML lol:
- GWML (up to Didcot)
- Cherwell Valley Line (up to Banbury)
- Chiltern Main Line (up past Small Heath, Birmingham)
- Camp Hill Line (to Birmingham NS)
After all that, it joins the WCML towards Wolves. It would be interesting to see what other route could be used if there were major infrastructure works being carried out north of Birmingham.