For the apportionment by county, are we looking at the immediate pre-1974 counties (so, for example - including Huntingdon & Peterborough; Cambridgeshire & Isle of Ely; Dudley transferred to Staffordshire; Smethwick transferred to Worcestershire; Greater London being in existence, etc) or boundaries further back? And within these 'new' old counties, are we looking at administrative boundaries within them as they are now, or as they might have existed at some previous date?
I'd go with the boundaries as existed (virtually) unchanged from the farreaching reforms in the 30s on to the mid-sixties changes (in Teesside and Shropshire, apart from the things you listed, possibly elsewhere that I'm forgetting); also for the next level in so far as available.
