There's apparently a good programme on Radio4 on Tuesday night about gerrymandering, only in this case its about Congressional boundaries in Texas, rather than the dynamic state of English rationality.
The relationship between regions, counties and UHF television transmitter coverage areas is always, I'd guess, going to be messy and political at any level of granularity as fine as a TV sub-region. This is essentially because over time the TV geography will begin to shape the boundary, and the urban hierarchy within the region; and so in part shape its politics.
For instance, in purely economic or social terms, Norwich is an insignificant place compared to Cambridge, or even Ipswich. Norwich has been able to pursue greater status, wealth and investment into institutions such as the UEA, simply because it’s seen as the "city of the region" in TV terms.
The whole concept of the northern home counties annexing the nicer bits of the East Midlands to become “West Anglia" was driven by the relatively larger coverage area of the Sandy heath UHF transmitter over its Channel 6 predecessor, and the activities of British Rail.
The region as currently defined, i.e. Northamptonshire, Cambridgeshire (soft boundary with E Anglia), Bedfordshire, non-Metropolitan Hertfordshire and NE Bucks includes the railway new-towns of Stevenage, Peterborough and MK. The northern boundary is the extent to which commuting toward Central London is significant in local labour markets, and the western boundary the M1/WCML corridor. The southern and eastern boundaries are the physical obstacles of the Chilterns and the Fens.
Sociologically Sandy Heath hasn't done a bad job in creating for itself a homogeneous TV region over these 35 years or so. Rather than, as some pundits here have suggested, being a type mismatch the region strikes me as being quite similar in its build, defined by boundaries where the similarity begins to skew away. Peterborough, MK, Luton, Northampton and even Bedford are quite similar places, only Cambridge stands out.
