As I understand it, the Conservatives are not against airport expansion per se, just a 3rd runway at Heathrow. The LibDems take a dim view of any expansion anywhere; and Labour put all their eggs in the Heathrow basket.
Ironically, I think the Icelandic ash cloud may just have reminded some people how important air transport is to people's jobs, families and the functioning of the economy. Let's hope there's a bit of respite now from airline and aviation industry-bashing.