A Bristol professor has contributed to a major new report on the pros and cons of different voting systems.

The report was launched at the British Academy yesterday, just weeks before the General Election.

It looks at whether the system for electing MPs should be changed and how a second chamber should be selected.

Professor Ron Johnston, from the University of Bristol and co-author of the report, said: "There is no perfect electoral system. In our discussion we outline the trade-offs that have to be made when choosing one."

With the prospects of a hung Parliament increasing, the Commons voting for a referendum on changing the current first-past-the-post system in 2011 and all three major parties now seemingly committed to a wholly or largely elected House of Lords, the review is timely.