Bizzare car park "x-files" incident

same thing in this report, lots of comments that may shed light on it. The likeliest sounding one to me is that microwave transmissions cause the anti code hacking to kick in on the car alarm which disables the remote (the one mentioned was a Clifford, but it may be that the ystem is the same for oem)

There have been reports of problems with car remotes in a certain hardware shop car park in my nearest town, but I have never had a problem there. It's on the edge of a light industrial area. I sometimes have trouble in our local Tesco car park, though. I find that moving a few feet makes it work again. Tesco is near to residential homes, and a car dealer. And Morrison's!

Car park lighting, maybe ? The Tesco carparks that I have seen seem to use discharge lighting of some description, probably HPS, but might be HPS + mercury (golden white). Some of these lamps use electronic ballasts, and a fault may have caused serious amounts of RF to escape, de-sensing the keyfobs ? Mind, if it was happening this morning as well, I guess the lights would have been back off, knocking that theory on the head ...

Arfa

Or maybe a `naughty` radio ham with a high power

Very common problem in France with early type immobiliser/alarms fitted to bikes. So common that the locals carry foil and use it shield the transmitter reciever in certain locations. There is a TV transmitter near the paeage south of Calais adjacent to a rest area. Mates bike wouldn't start there as the imobiliser would not reset. Shielding it with the breakdown van and it started! Stil cost him the 90 euro call out fee. I belive that the operating frequency of imobilisers was changed recently - newer ones are less prone to this effect I belive.

There's probably a Tetra mast nearby.

TETRA? Yes - thats what the curious French incident with the Blackbird was eventually blamed on.