The British electoral system is often defended for producing workable Commons majorities, with the governing party accountable to voters rather than to other parties (Popper, 1988; Chandler, 1992; Johnson, 1992; Johnson, 1998; Norton, 1992; Pinto-Duschinsky, 1999a and Pinto-Duschinsky, 1999b). But since the 1970s, this defence has been undermined by four developments: the decline of the cube law; the increase in minor-party seats; the decreased cohesiveness of legislative majorities; and the rise in pro-Labour bias. The first three developments make workable Commons majorities less likely, and the fourth may hinder accountability by letting a party come first in votes but second in seats. The nightmare scenario for first-past-the-post’s defenders is an election which produces a hung parliament with the Conservatives first in votes, Labour first in seats, and the Liberal Democrats holding the balance of power and insisting on proportional representation (PR) as their price for supporting a government.
These diseases poisoning first-past-the-post have not been properly recognised by its defenders or critics. Its defenders know that it is imperfect, but they have not grasped how unreliable it has become. Although most recent elections have seen large government majorities, this is partly fortuitous: the winning party has usually had a big lead in votes over the second-placed party. First-past-the-post’s frailties should be clearer once the winning party’s lead in votes shrinks.
Critics of the system should also take note. Several discuss the cube law’s decline, but I will suggest that the rise in minor-party seats is more important. The increase in bias, often mentioned by critics, may not be as troubling as many imply. Meanwhile, neither critics nor defenders of first-past-the-post have spotted that decreased legislative cohesiveness aggravates the other developments. Both sides of the electoral reform debate should attend to these findings....