PETROL prices could fall by up to 5p within a fortnight, bringing long-awaited good news for hard-hit motorists.

It was splashed all over the front page of the Daily Express on Thursday and doubtless sent a shiver down the spines of many people already fed up with the chilly spring.

But it didn't come from the Met Office. No, this prophecy of a truly out-of-season wintry month came from an independent weather forecaster, Piers Corbyn, using what he terms his "solar weather technique" which involves calculating how solar particles will interact with the Earth. However, Mr Corbyn, 65, who has a degree in physics and runs a company named WeatherAction from an office in south London, declines to disclose his methodology in detail.

There doesn't seem to be a meeting point between the Met Office and Mr C, and indeed, if you mention him to the chaps down in Exeter, the response is a world-weary sigh. "Piers Corbyn has never been able or willing to publish," says a spokesman, "detailed analysis of how he forecasts the weather".

Mr Corbyn's response to this is robust. "They're lying scum!" he snorts. "Because basically, whenever I've had meetings and invited them along, they've refused to come."

On his methods, he says: "We've published detailed results, or others have published detailed results..."

But the methodology...?

"We have published certain ideas..."

But not the whole thing in detail?

"Well why the f**k should I? The methodology is owned by the company, right? Why the hell do you drink Coca-Cola when the recipe is secret?"

Mr Corbyn will, though, give a generalised outline. "It's based on the fact that the weather and climate are controlled by activity from the Sun, and its modulation by the orbit of the Moon," he says. "It's a solar-magnetic-lunar system."

Reminded that all the world's national weather services use numerical weather prediction, he says: "Well, what they're doing there is delusional nonsense, because the weather is not controlled by the weather. It's controlled by other things, ie external factors.

"Their calling for more money to be spent on computers is just theft. All it will enable them to do is get the wrong answer quicker."

US experts, who work with police forces tracing missing people, created the image for the Sunday Express using FBI forensic computer techniques.

She looks a bit like one of the Doctor's earlier assistants.