On election day, SNP could get a million votes and 40 plus seats - and UKIP, five million votes and a handful of seats.

Such are the vagaries of the First Past the Post system. A voting system the Liberal Democrats have long wanted reformed.

As Keith MacDougall reports, the Lib Dems - who might get around 25 seats with three million votes - don't seem to be talking about it as much now, as once they did.