Aye, I've seen this one. I wouldn't rely on the database though, there's certainly a load of cameras missing around my neck of the woods.
It's a pity there isn't a comprehensive database of OS grid referenced cameras available. Most of us will know where the cameras are in our local areas, it's when you travel somewhere new you can come unstuck. An OS referenced list would be handy so you can upload them to a GPS as 'warning waypoints'.
Information on speed camera locations is patchy (unless you have Geodesy or similar). Some police forces have comprehensive lists of Gatso sites and locations where mobile radar/laser units are in use, sadly many forces don't.