All attention seems to be focused on the alternatives of a single-party majority government, another coalition, or a confidence and supply arrangement between two parties, after the 2015 election. These are not the only possibilities. The trends in the electoral arithmetic are making a minority government, without a formal agreement with another party, a more viable option.
At its peak in the 1950s, the two-party system left little scope for a viable minority government. With virtually all seats in the hands of one or other of the major parties, a minority government was mathematically an unlikely proposition and practically an unstable solution – it would have been at the mercy of the support of one other party.
In 1959 the Conservatives and Labour won all except six seats between them. The Liberals won the other six. A minority government would have been unlikely to have emerged, and if it had, it would have beholden to the Liberals.
However, by 2010 a total of 57 seats went to the Lib Dems, but another 28 seats were won by other parties or independents (since then Respect have also won a seat at the Bradford West by-election).
If this pattern of seats dissipating from the main parties continues, or even accelerates (which seems quite likely), the options for a viable government a few seats short of a majority are increased. A minority government could pick and choose where it could gain the support it needed on each individual vote, without being permanently beholden to any one party. This could be the shape of things to come. The whips would be very busy!