Last month, the Tories narrowly held on to the seat of Uxbridge and South Ruislip in a by-election that Labour expected to win. Many commentators chalked the party’s loss up to the unpopularity of the ULEZ scheme in London’s outer boroughs.

Khan said that expanding the zone at the end of this month “was a difficult but necessary decision” and vowed not to back down. Owners of non-compliant vehicles will face a £12.50 charge when driving into the zone.

Air pollution is estimated to be responsible for around 4,000 premature deaths in London each year while causing other long-term conditions such as stunted lungs and asthma.

Car and motorcycle scrappage funds were initially prioritised for low-income and disabled Londoners. But the latest scrappage grants will provide up to £2,000 to all residents of the capital with a non-compliant car or motorcycle. Businesses will also be given an increased scrappage payment of £7,000 for vans, an increase from £5,000...