A surveillance operation was set up, it was alleged, in Suffolk, where the company constructing the craft was based, and at Greenpeace's workshop in London. State-of-the-art equipment was used, and operatives reported that something sinister was taking shape. A picture of the project began to emerge: it was cylindrical and yellow. Could it possibly be ... a yellow submarine?
In fact it was a solar-powered survival capsule, equipped to carry a crew of three. It is immobile but can be airlifted on to land or sea. It is easy to understand how the mistake was made: even Greenpeace admits the "bright yellow cylindrical-shaped capsule looks like a submarine with no conning tower".
Less easy to fathom was who carried out the surveillance which led to the mistake. Scotland Yard's Special Branch says it has no knowledge of the operation. But a source said: "It wasn't us; I believe it was another agency, and the job may have been contracted out to private investigators."
A former police officer now in private investigations maintained: "There was an operation on around last March. Obviously certain parties were concerned about what exactly was being produced, and it was natural to carry out checks. I have been told that a government agency was involved."
Chris Rose, Greenpeace's campaign director, said: "We are regularly put under surveillance by a variety of public and private bodies. The capsule was built in March-April, and at the time we were told by very highly placed sources that the then Tory government and elements in the oil industry were convinced that we would do something spectacular to put the environment on the election agenda, and this could help the opposition parties."
The capsule was used by Greenpeace in July to "seize" the island of Rockall as part of the campaign to stop Atlantic oil exploration. It was also used in its "occupation" of the Stena Dee oil platform this month. BP, which had been involved in litigation with Greenpeace over Stena Dee, denied it had carried out the surveillance during the construction of the pod.