The House of Commons Transport Committee has said, in a report today, that the government should reject the Thames Estuary airport plan and expand Heathrow instead.
The plans for a new hub airport east of London, favoured by London Mayor Boris Johnson, are described as far too expensive.
More top news
Corbyn was unveiling a poster less than a mile away as Khan gave his final campaign speech to party supporters in London.
Hay fever is an allergic reaction to airbourne pollen. There are 2 million sufferers in London (that's one in 5 people).
The man suffered head injuries after falling from Westminster Bridge and landing on concrete steps.