No excuses mate. Sorry though. Really annoying. If we all drove perfectly, they'd have to raise road tax!
We have these speed devices in most our 30 KM school zones that generally tends to self regulates your speed, especially since the fines are double if caught. The police also have a number of portable radar devices (mounted on small trailers) that they move around to different locations in the 50 KM (30 MPH) zones. For information purposes only, no cameras (at this point). http://www.cbc.ca/news/canada/new-brunswick/school-zone-speed-signs-effective-say-police-1.1175800
Depending on which type of camera, you might get away with it. If it was an old Gatso, more than 80% of them don't have any film in them. It's one reason they are being replaced by the digital cameras that don't use film...
I've heard a different version of this when I was in Edinburgh at Uni. That said it happened on the M9 in Fife with radar based fixed speed cameras. Personally I think it might be an urban myth. (Albeit a funny one.) The reason I say that is, to my understanding, a Sidewinder missile is an air to air weapon system not an air to ground one and it is a heat seeking system not radar based. The anti radar missiles follow the microwaves from the emitting radar system back to source and are designated HARM (High speed Anti Radiation Missile.)