Boundaries update
The final section of the revised boundary recommendations, those from Wales, are now out. Most of the changes from the interim recommendations are shuffling about of a ward here or there - the biggest changes are around Cardiff and the valleys: the rather odd Heads of the Valleys seat has been abandoned and the salamandery Newport West and Sirhowy Valley has gone. Meanwhile a recognisable Cardiff Central has been resurrected. The return of Cardiff Central means the revised boundaries have one more Lib Dem seat and one less Labour seat. The changes now go out for a new round of consultation, after which the Commissions may make some final changes (from past reviews, these are quite rare and often minor tweaks or name changes) or confirm these as their final recommendations.
Adding all the revised boundaries together gives us notional totals for what the seats at the 2010 election would have been if counted on the new boundaries of CON 302 (down 4), LAB 222 (down 36), LDEM 51 (down 6), Others 25 (down 4). As ever, it is important to remember that there are (a) notional results for the last election, not what would happen now and (b) what seats would have been won if people's votes had been counted on the new boundaries, NOT if they had voted on the new boundaries. Some people would have actually voted differently had the new boundaries been in force, particularly wards moving into Lib Dem marginals. For this reason I suspect notional calculations underestimate how well the Liberal Democrats would actually have done on these boundaries.
On current boundaries the Conservatives need a lead of 11.1% to win an overall majority on a uniform swing. They need a lead of 4.1% to be the largest party. Labour need a lead of 2.9% to get an overall majority. If the two main parties had equal shares of the vote Labour would have 53 seats more than the Conservatives.
On the revised boundaries the Conservatives need a lead of 7% to win an overall majority, they would need a lead of 1.4% to be the biggest party. Labour would need a lead of 4.7% to win an overall majority. If the two main parties had equal shares of the vote Labour would have 16 seats more than the Conservatives.
Note that all these targets are on a uniform swing between Conservative and Labour, they aren't the same under all circumstances. Most notably, if Liberal Democrat support falls the sort of leads the parties need to get an overall majority get smaller. Given that the Liberal Democrats aren't very likely to get 24% at the next election based on current polling, I've also given some illustrations on what the picture would be if the Lib Dems were on 12%.
On current boundaries, if the Lib Dems fell to 12% then the Conservatives would need a lead of 5.9% to get an overall majority, the Conservatives would need a lead of 3% to be the biggest party, Labour would need a lead of 0.4% for an overall majority. If the two main parties had equal shares of the vote Labour would have 41 seats more than the Conservatives.
On the revised boundaries, if the Lib Dems fell to 12% the Conservatives would need a lead of 2.7% to get an overall majority. Labour would need a lead 0.4% to be the biggest party and a lead of 3.8% to get an overall majority. If the two main parties had equal shares of the vote the Conservatives would have 3 seats more than Labour.
Of course, to some extent this all academic as currently the boundaries look unlikely to go through, with the Liberal Democrats repeatedly stating they will not do a deal on the boundaries. However, there was slight movement on another front yesterday. It is broadly assumed that the Conservatives could strike a deal with the DUP to support the changes, as well as the SNP, who do very well out of the boundary changes themselves (they are the only party who wouldn't lose any seats at all). However, this would be not be enough to get them through. Yesterday, however, Plaid Cymru said they were also open to a deal to support the boundary changes in exchange for greater devolution to Wales.
On paper the Conservatives, SNP, DUP and Plaid together have a de facto majority in the Commons and could push through changes. In practice it still looks dubious, even if some deal could be struck (which is far from certain!), as it would require no Conservative abstentions or rebellions, and at least one Conservative MP has publically said he'll vote against it. My expectation is still that the boundary changes will not happen.
Full notional figures for the revised boundaries for England, Wales and Scotland are now available as a google spreadsheet here (note that I have not done separate notional figures for UKIP in Scotland or the BNP in Wales, they are lumped in with Others).
