Why is 4 the correct number and 20 not? Smaller franchises allows management to be more focused on their area. E.g. would you bin Scotrail off as that’s not a Big 4 company?
It lessens the number of companies involved and means more integration. Surely the less companies you have, the easier it is to manage the system. Timetable planning can presumably be simplified if it's all one company in a given area. For example if the vast majority of services coming into Birmingham or Manchester are London Midland, most of the timetable is operated by one company meaning an easier planning process. Granted some locations would have other companies coming in (e.g a London Midland-operated XC would go onto other companies' patches), but they managed it under the Big Four, why could they not manage it under privatisation?
I'm not necessarily saying the Big 4 was not the correct structure - perhaps a five-company set up of GWR, London Midland, LNER, Scotrail and NSE would be. But my main point is you lessen the number of companies to those which make most sense operationally, or even just have one BR plc.
Why are ROSCOs bizarre? Rolling stock generally has a longer lifespan than the franchises. Otherwise you’d have to have the winning bidder buy the rolling stock from the outgoing franchisee.
Again, why have short-lived franchises? Why not let a given company operate the services indefinitely, unless they break the terms and conditions and get "booted off"? And in that case, the replacement franchisee would inherit the stock, with stock costs payable to the government. Essentially you dispense with ROSCOs and have the government oversee stock transfer in the hopefully small number of cases where a franchisee misbehaves.
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Once again, ROSCOs mean more organisations involved in running the railway, hence more bureaucracy and more shareholders to be paid.
As for Southern, it was run as three separate geographical regions under BR. There’s not anything intrinsic about the way the pre grouping companies were merged together.
The network is a closely integrated one and has much in common e.g third rail electrification, and most services at the time were operated with inter-compatible 41x - 42x EMUs (on the mainline), or 455s (on the suburban - admittedly not the South Eastern). Essentially it was a common network. The big question really is why
not operate as one company, with three regional subdivisions? The aim of NSE was to move towards more integration across the SE, not less. Thus, as an alternative to an integrated SR, you could also have had a privatised version of NSE, operating all commuter lines round London.
We now have a situation where each part of the old SR is using incompatible EMUs. Imagine the operational advantages if the current SR used a compatible fleet of EMUs.
BR was seen as failing and the competitive environment could fix it, which BR plc wouldn’t do.
Failing by whom? IMX BR was doing really quite well in the (roughly) 1986-90 period, e.g. electrification, regularisation of timetables, renewal of stock. It was only the 1991 recession that put the kybosh on things, and would that have been any different under a many-company scenario?
Would BR have done badly under the better economic times of 1995 onwards, or would it have recovered?
You could still have competition with open-access operators, no need to carve up things the way they did.