More than 2,000 local residents would need to be rehoused under plans to build a third runway at Heathrow, it is being claimed.

The proposal to build a new north-west runway over the villages of Harmondsworth, Longford and Sipson would require the compulsory purchase and demolition of at least 783 houses, according to new calculations by the backers of alternative scheme Heathrow Hub.

As the average household size for the Heathrow villages is 2.7 people, it is estimated that alternative housing will potentially need to be found by the London Borough of Hillingdon for some 2,100 people whose homes are compulsorily purchased.

The Hillingdon council is currently controlled by the Conservatives and is being contested in local elections on May 3.

Heathrow Hub claims the airport’s scheme would also impact communities abutting the new airport perimeter, notably in Sipson and Harlington and Colnbrook.

A further 5,500 homes fall within a so-called wider property zone.

Within this zone “residents may have to move out of the area because of new and significantly adverse living conditions,” according to a recent House of Commons Transport Select Committee report.

Assuming the same household size, the zone encompasses some 14,850 people who might need new homes.

Heathrow Hub says its independent proposal to extend the northern runway destroys “far fewer” houses and has a much lower community impact.

The 242 affected houses are in Poyle and Colnbrook and are already at or near the end of the existing runway.

Average household size in this area is slightly smaller, at 2.4, making a total of 580 people.

Heathrow Hub estimates its scheme would result in an offer of purchase of a further 203 households and an offer of insulation to 1,975, mostly in Horton and Datchet. Many of these households already suffer noise.

While Heathrow has said it will meet the compensation bill for landowners, no thought has apparently been given to the cost or logistics of rehousing those losing their homes and unable to find suitable new accommodation on reasonable terms, Heathrow Hub claims.

Guidance on compulsory purchase from the Ministry of Housing, Communities and Local Government is that this duty to rehouse falls to the local authority.

Heathrow Hub director Jock Lowe said: “Our scheme was created from the outset to minimise the impact on local communities. The extension of the northern runway has a far lower impact on housing stock. It is a simpler, cheaper and quieter scheme.

“Heathrow’s current proposal will put local housing under much greater pressure, particularly in the London Borough of Hillingdon. The council will need to state how it intends to house a further 2,100 people. The lack of consideration in relation to housing is stark.

“We have written to Sajid Javid, the housing secretary, to ensure he is fully aware of the potential housing crisis in Hillingdon and Slough which Heathrow’s plans could cause. Local people are entitled to know how they will be rehoused and who will pay.

“It is not too late for the Cabinet to decide that the Department for Transport has made a mistake by allowing Heathrow airport to effectively veto our cheaper, simpler, quieter scheme, simply on the grounds it is cheaper and consequently makes less money for their shareholders.”