Zac Goldsmith MP joined the Mayor and hundreds of others in Barnes at a rally against Heathrow's third runway.
Richmond Council, which serves residents who live under the airport's flight path, is currently leading a referendum on the future of Heathrow.
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Police are investigating whether a Land Rover Defender found burnt out in West Horsley was involved in Tuesday night's ram raid.
The work, called Gift Horse, replaces the giant blue cockerel that previously sat on the plinth.
50 of the country's worst pollution blackspots are in the capital. Many in places you may visit every day.