The Fixed Term Parliaments Act 2011 set the date of the next general election (to the House of Commons only) to be Thursday, 7 May 2015 - thanks to the failure to introduce legislation for House of Lords reform, the Commons will be the only chamber at Westminster we'll be voting for, although I have looked at how House of Lords reform can be salvaged in line with previous proposals. And then every 5 years on the first Thursday in May, with certain exceptions.
The Scotland Act 1998 sets the elections to the Scottish Parliament to be every 4 years on the first Thursday in May from 1999 onwards. However, the Fixed Term Parliaments Act 2011 postpones the 2015 ones to Thursday, 5 May 2016.
The Government of Wales Act 1998 (now superseded by the Government of Wales Act 2006) sets the elections to the Welsh Assembly to be every 4 years on the first Thursday in May from 1999 onwards, just like the Scottish Parliament. And, just like the Scottish Parliament, the Fixed Term Parliaments Act 2011 postpones the 2015 ones to Thursday, 5 May 2016.
The Northern Ireland Act 1998 sets - yes you've guessed it - elections to the Northern Ireland Assembly to be every 4 years on the first Thursday in May, with the first elections being Thursday, 25 June 1998, and the cycle would then be 2002. 2006, 2010, 2014 etc.. However, the Northern Ireland Act 2000 allowed the Northern Ireland Secretary to suspend the Assembly, and under the terms of the Northern Ireland Assembly Elections Act 2003 the next election was on Wednesday, 26 November 2003. The Northern Ireland (St Andrews Agreement) Act 2006 set the next elections to be Wednesday, 7 March 2007, and since then the 4-year cycle in the Northern Ireland Act 1998 has re-commenced. That put the last elections on Thursday, 5 May 2011, coinciding with the Scottish and Welsh ones, so we would have expected the three non-English devolved legislatures to be elected at the same time.
But the Fixed Term Parliaments Act 2011 did not apply to the Northern Ireland Assembly, so in May 2015 the good people of Northern Ireland will be voting (using First Past The Post) for the House of Commons and (using the Single Transferable Vote) for the Northern Ireland Assembly, with the following Stormont elections being on Thursday, 2 May 2019.
The Greater London Authority Act 1999 set up the two parts of the Greater London Authority- the Mayor of London and the Greater London Assembly. It set the first election to be Thursday, 4 May 2000, and then the first Thursday in May every 4 years. So, the next one occurs at the same time as the Scottish Parliament and Welsh Assembly.
And this brings us to the Police & Crime Commissioners across England (outside Greater London) and Wales, elected under the Police Reform & Social Responsibility Act 2011, with the first elections having been on Thursday, 15 November 2012, and then on the first Thursday in May starting with 2016.
So, in May 2016 there will be 4 simultaneous elections covering all of Great Britain:
And these will be on the same 4-year cycle.
Not only that, but:
Now, if you have a 4-year cycle and a 5-year cycle, then every 20 years they coincide. And, when these are up for re-election in 2020, it will be alongside elections to the House of Commons.
This will be a general election where the whole electorate of Great Britain will not only be voting (using FPTP) for their MPs, but alongside that will be voting using SV and/or AMS.
As people enter the polling booths in May 2020, FPTP won't be the way we do elections here. It will be just one of the ways we do elections here.