UK parliamentary boundary review

[IceAgeComing]

Yeah I'd not trust Electoral Calculus's numbers - from memory their notional numbers were very different from the other calculations in 2010 (that do things in a more complex way) and based on the swings in them they were very far out.

Its come increasingly common to split wards when drawing up seats in the UK - especially in Scotland but also in some other places that have large populations and relatively small councils either elected by thirds or with three councillors per ward.  The main factor has been the shift to the 5% threshold - in Scotland especially that gives you very narrow leeway without splitting wards, and the results are never satisfactory because of that fact.  The pre-2015 review had some monstrosities in it (remember Mersey Banks?) and I think that experience made the Commissions a lot more willing to split wards to avoid those: better to split a few wards and get seats that all make sense over not splitting them and having a few really dodgy seats that are just the orphaned wards that you can't get anywhere else.

[IceAgeComing]

Local knowledge, hunches, intuition and an awareness of the fact that whatever methods you use; none of them will be perfect.

The other issue with using pure ward numbers is that tactical voting is a big thing; and so you can't assume that a ward that moves from a safe seat to a marginal or vice versa; or from a Labour/Conservative to Lib Dem/Conservative marginal will behave anything like it did in the last election.