That's all fine and dandy Sludgey but... picture the scene - Sir Keir and Angie have just completed the total re nationalisation - we are back to British Rail. Responsible for all trains, track, repairs, drivers, conductors etc - fantastic. Until British Rail union members decide to go on strike for more (insert ludicrous demand here).
All of a sudden with great ease - they could bring down the entire rail network. Every person now employed by the Govt. East coast service is cr@p - we'll get companies to re tender and dont renew the current supplier - under British Rail - you are stuck with them.
Inefficiency, no motivation to innovate, probable political interference, zero accountability, zero competition, if you want that good luck to you. Much better off using the Japan Rail model - rather than the usual socialist guff policy that never worked and will fail again. But hey ho - I'm sure you have thought this through - and it will all be fine - just like it was in the 70's