Off the top of my head, a few I can think of where they haven't been:
Hazel Grove to Buxton.
Edgeley Jn. to Chester via Altrincham.
Skipton to Carnforth/Carlisle.
Carlisle to Millom (if that's where they're banned from) via the Cumbrian Coast.
I don't think many have gone Edgeley Jn. to Stoke...