A spokesperson for the airport rejected claims that expansion was incompatible with net zero goals – and said the airport was committed to a completely privately-funded noise insulation scheme for local homes.
On transport infrastructure, Heathrow stated its expansion plans include widening a busy stretch of the M25, adding that it will present “viable and funded solutions” for required public transport upgrades as part of the planning process.
“This is about much more than a new runway.
“It’s about unlocking growth and over 100,000 jobs for the whole country, boosting British trade by £150bn, making travel more affordable and revitalising the UK’s steel industry.”
The mayor’s stance is backed by a coalition of London and home counties council leaders – including Wandsworth, Richmond, Kingston, Hillingdon, Southwark, Sutton, and Windsor and Maidenhead.
In a joint letter to Transport Secretary Heidi Alexander following the consultation’s close, the cross-party group called on the government to withdraw support for the third runway.
However, the Back Heathrow campaign pushed back against the councils, claiming their opposition was “not representative” of local residents.
Executive director Parmjit Dhanda said more than 100,000 local members support the expansion, citing the potential for jobs, trade, and economic growth, adding that a new runway was “way overdue”.
The Department for Transport, which threw its support behind expansion under Keir Starmer’s premiership in 2025, said ministers would “carefully consider all responses before setting out next steps later this year”.
“We have always been clear that expansion will only go ahead if it is delivered in line with our legally binding climate change obligations, and meets strict environmental rules on air quality and noise pollution,” a spokesperson for the department added.
Analysis: Tom Edwards, BBC London transport correspondent
The position of the mayor and TfL against expansion at Heathrow hasn’t changed -they have always had concerns over noise pollution, public transport and extra traffic.
What is different this time is they think the modelling is outdated, and the language seems to have toughened.
Perhaps Ulez has empowered the mayor to be more direct?
TfL said since the pandemic, the world had changed with a decline in business travel. They also said the figures being used to back expansion are over ten years old and no longer relevant.
It leaves the mayor potentially on a collision course with the pro-expansion lobby – including those within his own party.
