A motorway service station may not sound like a key election battleground, but according to psephologists, service stations - or rather, the people who regularly use them and live near them - hold the power to swing the outcome on 6 May.

As part of Newsnight's election coverage, Stephen Smith has decamped to Donington Park services on the M1 to meet the men and women who could have a big say in the outcome of the general election.