The expectation is that equalising electorate sizes will benefit the Conservatives by reducing the systematic bias to Labour in the system. It is also thought it may make it a bit harder for Lib Dems and others to win seats, but that may be more Tory wishful thinking than what would really happen, as I have not seen any academic research on the point.

The aspects of bias which will be corrected, in the new  system, result from Welsh seats and urban seats generally having tended to have smaller electorates. Before 2005 this also applied to Scottish constituencies. All the areas involved are more Labour inclined than the average British seat.

The other source of bias, that Labour voters are more efficiently distributed to maximise seat victories, is inherant in the single member constituency system. That bias can only be corrected by proportional representation.