On April 18, United Kingdom prime minister Theresa May announced that the country will hold a general parliamentary election on June 8, 2017. The decision is a surprise. The contrast between the United States and the United Kingdom could hardly be more pronounced, in the variable of advance knowledge of election dates. In the United States, if there were a general election set for June 8, 2017, federal law would require that ballots be sent to overseas absentee voters no later than April 24, which is only six days away. Obviously the U.S. needs months and months more preparation than the United Kingdom.
British parties already have chosen their national leaders some time ago, so that makes a snap election somewhat easier. But the British parties still need to choose their parliamentary candidates. British ballot access is so simple and uncomplicated, that helps also. Candidates for House of Commons need 10 signatures and a filing fee. All candidates are treated equally, relative to ballot access.