Alternative Vote

If we'd had the Alternative Vote system instead of the First Past The Post system, the Conservatives would have had roughly 38 fewer seats, which would have ended up split broadly between the Liberal Democrats and the Labour Party.

Disclaimer: I've only calculated this for constituencies where Lib/Lab/Con formed the top 3 parties, I've assumed the vote from the other parties is equally split across Lib/Lab/Con, and it's based on people's second-choice voting intentions from 2005.

I've not double checked my figures or anything, but they look broadly right. Where Labour have small majorities many of them tip over to the Lib Dems due to the typical Conservative voter's second choice favouring the Liberal Democrats, whereas mostly it's a case of the Conservatives losing to one of the other two parties.

                  Constituency -- Change of winner and their majority under AV
------------------------------------------------------------------------------
                       Ipswich -- C (2079) => Lab (317)
                      Rochdale -- Lab (889) => LD (1851)
                  Chesterfield -- Lab (549) => LD (1832)
            Bristol North West -- C (3274) => LD (1558)
      Wolverhampton South West -- C (691) => Lab (1110)
               Edinburgh South -- Lab (316) => LD (2804)
                 Cardiff North -- C (194) => Lab (2248)
          Camborne and Redruth -- C (66) => LD (2504)
                  Newton Abbot -- C (523) => LD (730)
             Northampton North -- C (1936) => Lab (1214)
                    Gloucester -- C (2420) => Lab (315)
                      Ashfield -- Lab (192) => LD (3338)
                     St Albans -- C (2305) => LD (1131)
             Brighton Kemptown -- C (1328) => Lab (826)
                       Waveney -- C (769) => Lab (1138)
                  Colne Valley -- C (4837) => LD (561)
                   Weaver Vale -- C (991) => Lab (1304)
                        Hendon -- C (106) => Lab (1500)
                Stockton South -- C (332) => Lab (1796)
      Oxford West and Abingdon -- C (176) => LD (2044)
            Truro and Falmouth -- C (435) => LD (1303)
                      Dewsbury -- C (1526) => Lab (1036)
       Morecambe and Lunesdale -- C (866) => Lab (806)
                       Lincoln -- C (1058) => Lab (1534)
                  Swansea West -- Lab (504) => LD (1940)
                  Amber Valley -- C (536) => Lab (1322)
                      Broxtowe -- C (389) => Lab (2105)
                        Stroud -- C (1299) => Lab (1208)
       Lancaster and Fleetwood -- C (333) => Lab (1954)
 Plymouth Sutton and Devonport -- C (1149) => Lab (1883)
            Warwickshire North -- C (54) => Lab (1480)
             Sheffield Central -- Lab (165) => LD (1223)
                       Bedford -- C (1353) => Lab (1155)
   Oldham East and Saddleworth -- Lab (103) => LD (3782)
                    Hull North -- Lab (641) => LD (800)
                       Watford -- C (1425) => LD (4032)
                      Carlisle -- C (853) => Lab (986)
                      Sherwood -- C (214) => Lab (1825)
              Hastings and Rye -- C (1993) => Lab (198)
   Harrogate and Knaresborough -- C (1039) => LD (224)
                         Corby -- C (1895) => Lab (299)
       Brentford and Isleworth -- C (1958) => Lab (1603)
                        Pudsey -- C (1659) => Lab (1203)
     Edinburgh North and Leith -- Lab (1724) => LD (612)
              Warrington South -- C (1553) => Lab (2673)
                      Thurrock -- C (92) => Lab (1280)
                          Hove -- C (1868) => Lab (1279)
                  Newport East -- Lab (1650) => LD (963)
C  : 300 -> 262  (-38)
LD : 48 -> 67  (19)
Lab: 209 -> 228  (19)