The idea of having to find a compliant path from Redhill to Brighton, somehow probably with a regular set of departure times, doubtful. Then there's the Downs, then there's Moreton Cutting / Didcot East, then you've got the Cherwell Valley, reversals in Birmingham New Street, the section from Derby to Sheffield, and the north ECML. Whatever modelling is being done, even if there is somehow five compliant paths each day, you'd have to say the benefit of leaving the space as a punctuality firebreak or even leaving it available for freight in some places...