BORIS Johnson has prompted fury by sailing into the Thames Estuary in search of a possible site for a new airport.

The London mayor was accompanied by a team of engineers aboard a 400ft dredger as he tested the waters for the proposal to build an airport on an artificial island in the estuary.

He hopes the move would be considered by the Government instead of a third runway at Heathrow.

But Rochford and Southend East Tory MP James Duddridge said he would fight the “ill-thought out scheme”.

Castle Point UKIP MP Bob Spink added: “In terms of airport safety it is not a runner, in terms of environmental and ecological impact it is not a runner. In terms of funding it makes no sense at all.

“Boris is a lovely man, but this is slightly bonkers.”

The RSPB said it would also oppose further airport expansion.

Plans for the £40billion airport involve creating two islands linked by a tunnel to Kent and Essex. Engineers believe it could be built within eight years.