The chief Liberal Democrat election strategist has said that the next general election could produce results that will re-open the debate over proportional representation.

"While not forecasting it, it's not at all impossible that the Liberal Democrats will overtake the Conservatives in sharing the vote," Lord Rennard told GMTV.

"We could well overtake them in sharing the vote but suppose they get more seats than we do, I think people would think that was perverse and not right."