Link the UK government's term length to their share of the popular vote.  Winning 30% gives a 3 year term, 40% a 4 year term and 50% a 5 year term.

For example, the current Government (with 34% vote share) would have received a 3 year term.  The previous Government would have received a 4 year term.

Details to note:

• Limits could apply, e.g. no less than 3 years and no more than 5 years.
• Parliament could still agree to an early election if needed.
• If a formal coalition agreement is signed the popular vote of the coalition parties could be combined.

This balances the decisiveness of the First Past the Post system with the checks on power and incentives for collaboration of a Proportional Representation system.   

It may be considered a reasonable compromise between the two systems and a way to explore evolutionary change without a massive disruption to the electoral system.

This petition calls for the above design to be considered in any public enquiries or reviews of the electoral system.