A new venue was looked for years ago and they couldn't find anywhere near(ish) to Brough. Tsunami could tell us all about that! Cambois was looked into, but I can't remember why that was knocked on the head.
It's not only finding a place to build a track, there is these days an insurmountable amount of Red Tape to plough through. Exeter springs to mind and they've been looking since 2005 (there are others who have found a place and then got no further, despite all the positive display of public announcements).
Oh and as a P.S. Would the BSPA allow a track share? Bearing in mind Cradley and the like have been told they can't run while sharing a track?