A salesman accused of marketing useless bomb detectors believed the machine had located Madeleine McCann, he told the Old Bailey today.

Simon Sherrard, of Hill Rise, Hampstead Garden Suburb, said the phony Alpha 6 device had indicated roughly where the missing girl was.

“She was either in Ireland or somewhere in middle or Northern Europe,” he said.

He even called the missing girl’s hotline to tell them where Maddie was.

Sherrard, 50, described how he located her by taking the device into London and “walking in circles three metres in radius”.

Using this method, Sherrard claimed it was possible to “triangulate” Maddie’s position.

His business partner Sam Tree, accused of manufacturing the devices, even travelled to Ireland “on the trail” of Maddie, the court heard.

Prosecutor Richard Whittam QC asked: “You believed that the Alpha 6 device, programmed with a photograph of Madeleine McCann, could operate through London and all the people there and into the continent?”

“We had belief in the equipment”, Sherrard replied.

“Were you trying to think of a way to make some money out of that exercise?”, asked the prosecutor.

Sherrard denied that the claim was a cynical marketing ploy to cash in on the notoriety of the McCann case.

They had only rung the Madeleine McCann helpline to share their discovery, he said.

Mr Whittam said: “I suggest to you that you knew full well that the “Alpha 6” did not work.”

“You are entitled to your opinion”, Sherrard replied.

The devices sold for up to £13,200 a piece but were in fact useless, the court has heard.

Sherrard denies supplying an article for use in fraud.

Tree and his wife Joan, 61, of Houghton Road, Dunstable, deny making an article for use in fraud.