Reading an earlier post on nodal points and East - West rail, I have an idea in my head.
The XC network could simply run from Liverpool, Manchester, Leeds, and York in the north via Birmingham to Cardiff, Bristol, and Reading in the South. This would form the "core" of the XC services.
The Liverpool and Manchester departures could run every 30 minutes by running along the Liverpool & Manchester Railway to Earlestown and then the Grand Junction to Warrington Bank Quay. The services could couple/detach at WBQ (4 Platforms, so out of the way of ICWC services) and proceed via Birmingham to Reading. Obviously, Stockport would no longer directly be served, but there are services to Crewe where passengers can connect into.
One train could start from each of York and Leeds, with the York service calling at Doncaster and the Leeds service calling at Wakefield (either Westgate or Kirkgate - if Kirkgate, then maybe also Barnsley), where both the services would couple up or detach at Sheffield. This would require planning at SHF so as not to get in the way of the Lincolnshire/Hull Paragon/St Pancras services that use the through platforms. The services could detach/couple up at Bristol Parkway, but again, would get in the way of the ICGW services to/from Paddington, and would involve coupling up/detaching twice during the same journey. However, it would give a frequency of every 30 minutes between Sheffield and Bristol Parkway via Birmingham.
Alternatively, the Leeds service could run to Cardiff Central via Bristol Parkway, with the York service running to Bristol Temple Meads, with both running as double formation which would be a lot easier. Again, it would provide a frequency of every 30 minutes between Sheffield and Bristol Parkway. Obviously, this would reduce Bristol Temple Meads from every 30 minutes to every 60 minutes, hence the Cardiff service being routed via Parkway to provide connections.
What about the section between Bristol and Devon/Cornwall, and Reading and Bournemouth? The paths vacated could be used for the East - West Rail scheme, with an hourly Plymouth via Bristol, Swindon, Oxford, Bedford Midland, stations via Sheffield to Doncaster, then calling at York, Newcastle Central, and Edinburgh Waverley.
The Bournemouth to Reading section could continue as above via the East - West Rail to Edinburgh Waverley, giving a frequency of every 30 minutes between Edinburgh and Oxford.
I know this seems somewhat controversial, as there would no longer be any direct services between Birmingham and Devon/Cornwall, but my idea was by reducing the distance of the present XC intercity services that run through Birmingham i.e making it into a medium - distance regional service, the services from points further south could then be a true Intercity type service with proper coaching stock, by running over the E-W Rail link, with the medium distance regional services via Birmingham running in 2 units coupled up for the majority of its distance.
What do people think - a reasonable idea, or have I argued with myself and answered my own questions and go back to the drawing board?
In peace
Adam