From Electoral Calculus
There has been recent interest in the likely effect of new boundaries which may be brought in under this parliament. Electoral Calculus prepared a full set of notional implied results under the 600-seat "Sixth Periodic review" of boundaries which was conducted around 2013.
Although these boundaries were not used in 2015, they can still give a good approximation of the likely effect of the boundary changes. If we use the actual election result (adjusted slightly to compensate for model deficiencies) and feed it into the user-defined predictor, then we can see the effect of the boundaries.
- Verify 2015 using old boundaries (Seat Boundaries = "Historic 2010 election")
- Predict 2015 using new boundaries (Seat Boundaries = "Proposed 2013 boundaries")
Using these figures and the old boundaries gives CON 331, LAB 232, LIB 9, UKIP 1, Green 1, SNP 55, and Plaid 3, which is almost exactly correct. Then when we switch to the proposed 2013 boundaries we get
This gives the Conservatives a majority of 50 seats, well ahead of their current majority of 12. This is equivalent of nearly another twenty seats for the Conservatives.
Without any change to legislation, the Sixth Review should restart this year for completion in 2018. It looks unlikely that the Conservative government would want to slow this process down.