As the Conservatives took their battle bus off the road after it was pointed out that its tax disc had expired, the transport secretary said road tax could be scrapped.

Alistair Darling says a new national system of road pricing could be given the go-ahead by the halfway point of a Labour third term.

In an interview with the FT, he says he will be "taking this forward" early in the next parliament if re-elected.

"There has to be a strategic decision in the next two to three years as to whether this works," the Cabinet minister makes clear.