Euston station "no longer in fit condition": how should this problem be resolved?

[Bletchleyite]

If money were no object I'd try to put another concourse in and either separate them by entrance and exit or switch the existing one to be purely serving the suburban platform entrance.

Not sure how you'd get additional escalators in to serve a new concourse though as the circulation spaces are quite compact.

It would be possible to improve it by having entrance gates in the centre and exit gates at the sides with the choice of whether to go to 8-11 or the main exit made before passing the gate line. This would also involve changing the escalators round and relocating the TVMs. There would still be conflicts but much reduced.