I've always wondered if the government could defray the cost of HS2 by buying some blocks of cheap farmland in the middle of nowhere, adding a HS2 station so the land was 20 minutes from central London, then selling the land to property developers. Obviously you could only add one or two towns, to avoid creating slow stopping services.

Seems to me that could increase the housing supply and offset the costs of HS2 at the same time - and most governments have had plans for new towns, new garden cities and suchlike.