If you fancy a flutter, you might want to keep your money in your pocket when it comes to the Thames Estuary airport.

Renowned architect Lord Foster's plan for a multi-billion pound airport on the Isle of Grain has been described as a "long shot" by bookmakers William Hill, who have given odds of 6-4 that work on the huge project will be under way by 2020.

Bet the other way and you will get an even more meagre return.

William Hill is offering odds of 1-2 that work will not have begun on the airport by the turn of the decade - meaning you'd have to place a £2 stake to win a quid.

Spokesman Rupert Adams said it all comes down to money.

"Local opposition is a stumbling block to it, but not the main stumbling block," he said.

All three of the Towns' MPs, Medway Council and the RSPB are opposed to the proposal, which would cost £50 billion and have four runways.

Lord Foster's ambitious proposal for Thames Hub would include a huge flood barrier and the country's busiest railway station beneath the airport terminal.

The airport would handle 150 million passengers a year and flights would land 24 hours a day.

However, Mr Adams said it is hard to see the money being available soon.

He said: "The simple reality is that you have got to find the money for the project and we can't see the cash being available in the near future.

"You might find it will take 50 to 100 years to reclaim the cost and we can't see private companies spending the money.

"We don't necessarily think it's a bad idea - we think it's a potentially great idea - but it's a question of coming up with the funds."

Medway Council leader Cllr Rodney Chambers said he would not even give the idea "a one-in-a-million chance of ever getting off the ground".

"The case against an airport on the Thames Estuary couldn't be stronger," he said.

"The Prime Minister has dismissed the proposal, the airline industry are opposed to it and a recent poll by ICM for Medway Council shows that 76% of people across the UK are against the idea. This pie in the sky idea is a complete pipe dream."