The Government has denied there will be any cost to the taxpayer for Heathrow’s third runway after a letter from Richmond Council’s leader demanded the hidden costs be revealed.

The letter, signed by three other leaders, six MPs, and two members of the House of Lords, stated there “will be a price to pay for Heathrow expansion” and that the Transport Secretary “has a duty to spell out the true cost for taxpayers”.

In response, a Department for Transport spokeswoman said: “We have been very clear that Heathrow expansion will be delivered and funded privately.

“Heathrow has committed to funding any surface access improvements required to deliver expansion.”

However, the letter was concerned with future costs such as failing domestic flights.

Leader Councillor Paul Hodgins wrote: “You only have to look at BA’s recent decision to halve the number of flights between Heathrow and Leeds Bradford to see how fragile domestic services are.

“Which minister can guarantee in perpetuity the taxpayer subsidies that would be needed to keep ‘unprofitable’ routes open?

“It is far more likely that the eight domestic routes we have today will shrink.

“The Airports Commission saw these dropping to four by 2030.

“The only way existing routes can survive – and new routes can be made viable - is if they are subsidised by the Government. They cannot be guaranteed.”

Cllr Hodgins went on to say that the alternative- Gatwick expansion- would “produce greater economic benefits”.

He said: “Gatwick is also likely to prove much more attractive to the low cost operators who ultimately will be the most likely to make domestic services work.

“We should also look to provincial airports to meet some of the increased demand.

“Birmingham, Manchester and other airports in Scotland and the North are already doubling direct flights, including some to rapidly expanding emerging countries in Asia.”

The letter, signed by council leaders Ravi Govindia, Ray Puddifoot, Simon Dudley, MPs Zac Goldsmith, Sir Vince Cable, Andy Slaughter, Ruth Cadbury, Marsha de Cordova, Justine Greening and Baroness Kramer and Lord True, finished by stating “no one can say with any certainly what the rules will be” once the third runway is finished.