To clarify: five models for privatisation were put forward by different groups (the Cabinet Office, the DfT, the Treasury and outside parties) at different times. Very briefly these were:
- Regional - essentially re-creating the ‘Big 4’ (but could have been up to 12)
- Track Authority - but see below
- BR plc
- Business Sectors
- a hybrid of the above.
So several models were available - and the supporters of each produced their own arguments. The was no ‘basic premise’ apart from the feeling that costs could be reduced and the quality of service improved if the private sector were to be involved.
The first two options were produced by right-wing ‘Think Tanks’, the Centre for Policy Studies and the Adam Smith Institute. They both proposed breaking up BR before privatisation, but for different reasons.
The concept you mention, of on-rail competition with a separate track authority with the train operators bidding for paths, was proposed by the Adam Smith Institute following a similar line of thought which led to bus privatisation and deregulation in 1985.
The results of the bus policy was not as successful as its chief protagonist, Nicholas Ridley, had envisaged, (partly because of the weak financial position of many of the bus operators - which was even more obvious in the case of BR and its continuing subsidy) and in the
final run-up to the Railways Bill the idea of on-rail competition was dropped because the Government didn’t again want to suffer the bad press that it received after the bus business.
There were all sorts of arguments within the working groups on how to handle the necessary on-going subsidy and
it became clear that bidding for paths on a monthly or bi-monthly basis was not applicable for railways because of the inter-related nature of its operations. So that was dropped as well. It was decided the best way to handle the subsidy issue was for potential train operators to bid for a group of services - a clear figure was available for each area and any cross-subsidy between profitable and loss-making services was up to the individual operators to manage. This avoided the DfT having to identify costs and revenues on an individual service basis.
So, although on-rail competition was considered in the early phases of the privatisation debate it was dropped as it wasn’t compatible with the realities of railway operation. There is a good description of the events and discussions leading up to the Railways Act 1993 in the book
All Change. British Railway Privatisation edited by Freeman and Shaw and published by McGraw-Hill in 2000.