Over here, national congressional districts are redrawn after the decennial census. Unfortunately, even though the districts end up having the same number of people, usually the incumbents (of both parties) determine where the boundaries are. What that means is there's usually bargaining to keep most of the minority incumbents in office (to gain their support), while the majority draws the lines so that they win a few more marginal districts to increase their majorities. Sometimes, though, the majority simply rams through the changes they want and the ones they think they can get away with (see Texas and DeLay).
This means they have a larger majority in the House of Representatives than they "should", but it makes the majority fragile to demographic change or relatively small changes in views of the electorate. It makes "wave" elections more likely.
So while over here the Republican's have a ~ 33 seat majority in the House (when they should be in the minority) - 17 needed to flip the majority, by 2016 or 2020 or 2024 they risk having a ~ 40+ seat minority and having a tough time getting it back. Especially if their attempts at disenfrancisement are slapped down... Non-partisan redistricting in California changed the game there - it would be nice if something similar became a universal system.
I don't recall hearing about "redistricting" in the UK. Do similar things happen there, or is the population so stable that it's not needed? How are House districts done there?
Thanks.
Cheers,
Scott.