London divided over Heathrow
There is a YouGov poll of Londoners in the Evening Standard asking about Heathrow expansion. Slightly more people oppose the 3rd runway than support it, but it is hardly overwhelmingly: 43% opposed compared to 35%. Unsurprisingly, people in West London are more hostile towards the runway, 50% to 37%. Also, like nuclear power, is it one of those rare issues where there is a really stark gender divide - 45% of men support a third runway, but only 26% of women do.
Questioned on the issues surrounding the expansion, 58% of people think that expansion would be good for jobs and good for the economy, but 58% of people also believe that it would cause unacceptable levels of noise. On the wider question of principle, 39% of people agree what "Given the dangers of climate change we should not be expanding air travel at all", 47% of people disagree.
Note that someone on Guido's blog posted some figures claiming to be voting intention figures from this poll. I can confirm that they are total nonsense (for the record, the sample size and dates the person gave were also rubbish. My guess is that it was entirely made up).