My ideal network would require much more extensive electrification, and a unified rail passenger operator. Each line involved would retain at least one train per hour, but with some changes of destination from hour to hour.
So, for example for trains though Birmingham:
Manchester - Birmingham hourly, then in alternate hours to Reading/Bournemouth or Bristol / Plymouth.
Liverpool - Birmingham hourly, then as above to Bournemouth or Plymouth.
(Those Liverpool services would call only at Runcorn, Crewe, Stafford & Wolverhampton before Birmingham)
York - Leeds - Sheffield - Birmingham hourly then as above to Bournemouth or Plymouth.
Newcastle - York - Doncaster - Sheffield - Birmingham then as above to Bournemouth or Plymouth.
That combination would give 2 tph from Birmingham to both Bournemouth & Plymouth
(Between Birmingham & Bristol, they would call only at Cheltenham & Bristol Parkway)
Lincoln - Nottingham - Derby = Birmingham - Worcester - Hereford semi-fast. 1 tph
Lincoln - Nottingham - Derby - Birmingham - Cheltenham - Gloucester - Cardiff - Swansea semi-fast, 1 tph
Birmingham - Bristol stopping train, calling at University, Bromsgove and all stations via Gloucester. At least 1 tph, maybe 2 tph at Peaks.
Birmingham - Worcester - Hereford stopping train, 1 tph (as now), but possibly extended to Newport & Cardiff.
(Great Malvern) - Worcester - Bristol - Weston Super Mare stopping train, all stations via Gloucester 1 tph
Birmingham - Leicester - Peterborough hourly, then in alternate hours to Norwich & Yarmouth or Cambridge.
(East of Peterborough, these would alternate with Liverpool/Manchester services.)
Liverpool - Birmingham stopping service, hourly, calling at South Parkway & all stations to Wolverhamton, plus Galton Bridge.
Manchester - Birmingham stopping service, hourly, calling all stations via Stoke to Wolverhamton, plus Galton Bridge.
It is assumed that it would be after 2030/2035 before such changes could be adopted and new stock would be required. All trains would be at least 5 or 7 coaches, preferably without wasting space on underused 1st Class.