On Wed, Oct 10, 2012 at 02:42:10PM +0100, tim..... wrote:

Someone must have considered it commercially viable (on say, a 40 year
timetable) as otherwise it wouldn't have been built.

Not necessarily. You can argue that the role of the state is to make
sure that socially beneficial things get done even if not commercially
viable, such as provision of Radio 4 and the original Dartford Tunnel.

--
David Cantrell | Cake Smuggler Extraordinaire