Last Saturday I revealed that Danny Alexander will use the Lib Dem conference to articulate his differences with Tory partners over green energy and employmeng legislation.

The event is likely to see many more moments of differentation, and not only from the usual suspects such as Tim Farron or Vince Cable.

On transport, too – and in particular aviation – the Lib Dem motion at conference is a reminder of the gulf between the two parties on issues of policy.

While the Tory leadership (if not transport secretary Justine Greening) has swung behind a third runway at Heathrow, the Lib Dems are determined in their opposition to the scheme.

The motion says that Heathrow is “extremely badly located” and repeats that the Lib Dems remain “strongly opposed to the third runway“.

It repeats the coalition rejection of new runways at Heathrow, Stansted or Gatwick. It then goes further and voices opposition to mixed-mode at Heathrow, which the Tories are keen to push as an interim measure for the next three years.

(I revealed on July 1 that the coalition has put any aviation decision into the long grass until 2015 and that the Tories will not mention Heathrow in their manifesto to enable a U-turn in the next Parliament.)

The Lib Dem motion, from backbencher Julian Huppert (who has a Read more