RADICAL plans to build an airport on a man-made island in the Thames have been gathering pace this week.

Despite the the economic downturn and a lack of support from his own party, London’s Tory mayor Boris Johnson is ploughing ahead with investigating the idea, seen as an eco-friendly alternative to a third runway at Heathrow Airport.

This week, MPs set up a cross-party group to lobby the Government to investigate the idea and the mayor’s office confirmed a feasibility report should be published in the new year.

Also this week, Doug Oakervee, chairman of Crossrail and the lead engineer in the construction of Hong Kong International Airport, has been in talks with the mayor’s team over heading the study.

Hong Kong’s new airport was also built on reclaimed land with the involvement of British engineers, and the mayor’s administration believe this proves a similar scheme could work here.

So far, where the island would be remains sketchy, though there is speculation it would be between the Isle of Sheppey and Southend seafront, would have four runways and could be made from landfill.

Richard Brookes, Mr Johnson’s spokesman, said: “The mayor remains keen to know what the alternatives are to expansion at Heathrow to ensure the economy of the capital is secure and grows. Therefore, he wants to explore whether the idea of a new airport in the Thames would be viable. In the mayor’s Way to Go! transport report for the year, Mr Johnson describes the idea as “gaining strong support in Parliament and among the public”.

However, south Essex politicians, who have seen a number of similar schemes flounder in the past, are sceptical over whether the latest plans will ever take off.

Southend Council’s Tory leader Nigel Holdcroft said: “Because of the massive cost and the infrastructure necessary, it’s not likely to be realistic.

“One can see the attraction of aircrafts taking off and landing over water, rather than over land.

“But unless they have established funding will be available, they have to be careful not to waste everyone’s time and trouble.

“It has that ring of Maplin Sands about it, which wasted a massive amount of time and effort in the 1960s and 1970s.

“I’m not even sure where this man-made island would be located.”

Castle Point Council leader Pam Challis said: “As far as we’re concerned, anything which impacts on Canvey we would be strongly opposed to.

“We will have the new Shell Haven superport active over the next decade, so there will be a lot of shipping traffic in the Thames.

“There would have to be a huge ecological study before it got off the ground. One would question whether it’s economically viable.”

Meanwhile, Mr Johnson’s own party appears lukewarm over the idea, although they also oppose a third runway at Heathrow.

Tory leader David Cameron favours a high-speed rail link between London, Birmingham, Manchester and Leeds.

James Duddridge, Tory MP for Rochford and Southend East, also supports this alternative.

He told the Echo last month: “Boris has a thousand ideas, some of which are brilliant, some of which are less brilliant. The proposal for a Thames airport has not been thought through.

The UK’s largest trade union, Unite, has already criticised the idea due to its potential impact on jobs at Heathrow Airport, and for the lack of local infrastructure.

The Royal Society for the Protection of Birds also disapproves because of the potential environmental impact.

Canvey has an RSPB nature reserve, home to an array of wildlife, and the Thamses Estuary is used by about 30,000 migratory birds.

RSPB south east director Chris Corrigan told the Echo in September: “To build an airport there would be the biggest single piece of environmental vandalism ever perpetrated in the United Kingdom.”