Ambitious plans for a new high-speed railway which could take passengers from Kent to Gatwick airport in just 25 minutes have been revealed.

Engineering consultancy Expedition is behind the £10bn proposal, which bosses have described as the ‘M25 for high speed trains’.

Dubbed HS4Air, it would connect the existing high-speed rail line in Ashford to the planned HS2 project along a route that passes via both Gatwick and Heathrow airports.

Scroll down to see the planned route

The 140km-long line would link Kent to major cities north and west of London including Birmingham, Manchester and Cardiff – without taking passengers through the capital.

Expedition director Alistair Lenczner, who has led the development of the proposal, says it would bring a “massive economic benefit” to Kent.

He told KentOnline: “Ashford would become a boom town – passengers could get from Ashford to Gatwick in between 25 and 30 minutes and 45 minutes to Heathrow.

“I think because people would be able to get to the airports so quickly, it would make Ashford and Kent more appealing.

“It would link Kent to the rest of the country and people wouldn't have to go through London to get to other places.”

Bosses would upgrade the existing train line between Ashford International and Tonbridge to cater for the high-speed service.

'HS4Air can be regarded as a high-speed railway version of the M25 around London...' - Alistair Lenczner

Being almost dead straight, it is thought the stretch can be easily upgraded for the running of high-speed trains.

After that, HS4Air would run in tunnels to avoid adversely impacting on environmentally sensitive areas such as the Surrey Hills.

Mr Lenczner was previously involved with the Thames Estuary Airport plan, commonly known as ‘Boris Island’.

He added: “We are taking a pragmatic approach with the plan.

“The proposal is complementary to the current infrastructure in place and we are talking to people who we think will be interested in it.

“We are trying to encourage people to see the benefits and we think it is a very good proposal.

“If you want to get to Birmingham from Ashford, for example, there is no direct service at the moment but this would change that."

Mr Lenczner thinks the scheme can help the whole of Kent, not just Ashford.

He says residents in Canterbury, Folkestone and other areas could easily to get to Ashford International where they could then board a HS4Air train.

He added: "In a way HS4Air can be regarded as a high-speed railway version of the M25 around London, except that it allows much faster journey times with no congestion and with far less impact on the environment.

"HS4Air has been developed to allow rail and aviation infrastructure projects in south east England that are currently unconnected to become joined-up.

"This will offer greatly enhanced benefits for users and provide better value for the investments currently being made in the UK’s strategic infrastructure.”

It is also thought the proposal would alleviate pressure on the M25 and the number of domestic flights involving Heathrow and Gatwick.

Mr Lenczner says he is now in talks with "various parties" about taking the scheme forward.