Street Lamp Interference (SLI) isn't something many people have heard of. Which makes the concern and relief of those who write to Hilary Evans's office in Blackheath, London, seem even more genuine. "I have this problem," begins one letter. Another states: "I couldn't believe this was a phenomenon that others shared with me. I just thought I was nuts."
A respected investigator of the paranormal, Mr Evans co-founded the Association for the Scientific Study of Anomalous Phenomena (Assap) in 1981. But it was only five years ago that he set up Slide - the SLI Data Exchange - after people confessed their close encounters to him at lectures and asked him if any research was being done. It wasn't.
"I get a steady trickle of people writing in," says Mr Evans. "There is definitely something going on here. We may not know what the mechanism is, but the effect is real. We're not chasing an illusion."
Slide's database is a steadily growing collection of accounts, around 120 to date. "I was dating a girlfriend who lived across town from me," writes Bob Lovely from Montana, USA. "As I accelerated across the freeway entrance, each lamp I passed would go out just as I passed it. This was invariably on evenings that we had sex!"
Ronald Brown of Washington mentions a slightly more unpleasant experience: "I was once stopped in a major city by police officers, who wanted to know what I was doing to the street lights. They'd seen that as I turned into a street, each and every lamp went out as my car reached it. They searched me and my entire car before allowing me to leave."
Another witness was on holiday in Tenerife: "I liked to stroll on the marina last thing at night. As I passed each street lamp, it went out. As I approached the next one, the previous one came on. After three nights, it really spooked me. It happened every night for two weeks."
You would be forgiven for thinking that all this smacks of re-runs of The X-Files and too much cheese before bedtime. But if those who report SLI - Mr Evans calls them "sliders" - are involved in some mass conspiracy, then a lot of effort is going into it. People are taking the trouble, he says, to hunt down his address and compose letters just for the chance to be believed.
"People are frightened of being ridiculed by their colleagues," Mr Evans says. "That's why no progress is made in the field of paranormal research. There are so many obstacles to knowledge. More research into this ought to be done, and it ought to be done by scientists." There is hope. The London-based Society for Psychical Research has offered to begin formal investigations, though a date has not yet been set.
Most SLI cases are from the US, a fact which slightly disturbs Mr Evans. "It could be simply that it has received more publicity there than anywhere else. Or it could be that Americans are more gullible than other people. That's something we have to take into account. But it hasn't shaken my conviction that there's something funny going on."
It isn't funny to everyone, though. One British teenager found out about SLI the hard way, when he and a friend fled down an alley in panic after each lamp they passed under started blowing out. At the time of his report, he had never heard of Street Lamp Interference. And it's partly this lack of awareness, Mr Evans says, that is holding up the search for an answer.
As a scientist, he is reluctant to put forward his theory, and certainly not willing to back suggestions of poltergeists, black magic or spirits with a vendetta against lighting engineers. At least, not yet.
Curiously, there appears to be a tentative link between SLI and emotional state. Students report SLI during periods of intense stress. And the American slider David Kozbial says: "Most times I have been concentrating on something. The comic serendipity of the light blinking out in my peripheral vision usually relieves some of the tension."
Having seen corn circles exposed as a fraud, the Shroud of Turin proved a fake, and even Nessie given a severe beating with the debunking stick, the world is sorely in need of a new mystery. SLI might be just what the witchdoctor ordered. Fox Mulder, eat your heart out.
If you have experienced SLI, please write to Hilary Evans, Slide Project, 59 Tranquil Vale, London SE3 0BS.