Kent hosted the people who could make or break plans for the world’s biggest airport in the Thames estuary.

Public and press alike were strictly barred from the gathering by the Airports Commission.

It is believed three members of the panel - its leader Sir Howard Davies, fuels expert Vivenne Cox and Olympic Delivery Authority chairman Sir John Armitt - visited RSPB activists on the Hoo peninsula and met MPs and councillors for lunch at the St George’s Centre, Chatham Maritime.

Other delegates came from the National Grid, who own the £1bn Grain LNG on the site of Lord Foster’s airport plan, the Friends of North Kent Marshes and pro-airport group Demand Regeneration in North Kent (DRINK).

RSPB spokesman Rolf Williams was given half an hour with the panel at the bird charity’s Northward Hill reserve near Cooling.

He said: “The Thames estuary is an example of sustainable development - just look at the London Gateway port across the river. But something on the scale of an airport is totally beyond that.

“I think it’s telling that they wanted to see it themselves. I don’t think Boris Johnson’s ever stood at our viewpoint and taken in the view.”

Though he added: “It was pretty grey and miserable and I think they were quite happy to get back in the warm.”

Medway Council deputy leader Cllr Alan Jarrett (Con) claimed an airport would cost up to £80bn and the workforce would require “a new town the size of Manchester”.

He added: “The commission are on a series of fact-finding trips to look at all possible ways the government could bring about a rapid increase in aviation capacity for the UK.

“Building a huge hub airport from scratch would take at least 25 years. This is too late to stop the UK’s continued slide against its other competitors.

"Building a huge hub airport from scratch would take at least 25 years"

“It would also lead to the closure of Heathrow, which would devastate the economy to the west of London, and could lead to many multinational companies with European headquarters there simply moving abroad.

“Our solution is to make better use of existing airports, including here in Kent at Manston and Lydd, with better rail links to improve connectivity to places such as Stansted and Gatwick.”

But DRINK spokesman Clive Lawrence, who gave a 10-minute presentation pushing the need for jobs, said: “I really think this is going to happen. I think we will get an estuary airport.”

The commission will report at the end of the year outlining how Britain could tackle its air capacity - which could include plans in the Thames estuary.

It has already met London mayor Boris Johnson, prime minister David Cameron and aviation bosses from New York, Schipol in the Netherlands and Hong Kong.