Change the General Election format so that it is fixed, with one-fifth of seats contested each year in the first week of May just like local government elections. The Government cannot choose the date, it is fixed by Parliament.
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At present, the Government can choose when to have the GE, up to five years after the last one. In the interim, there is nothing the electorate can do if the Government does the opposite of what they promised in their pre-election manifesto. If one-fifth of the seats are up for grabs every year, then an unpopular Government would lose its majority and have to change direction. A popular Government could strengthen its control and ensure they could make more changes.