Last week I had the misfortune of having to drive through Harrow (NW London). At one point there was a road narrowing thing, 2 bollards in the centre of the road with "Bus Gate" painted in the road, no gate or barrier. As I was in the SUV and the gap either side of this "gate" was pretty narrow I drove through the centre. I should point out that this was at around 5 in the morning so doubtful there were any buses running then. I'd also been up all night at the hospital with step-son who had managed to seriously damage his knee and didn't see any warning signs before I went through the gap. A few days later I got a £65 fine for driving in a bus lane! I went back to check and the signs are not at all obvious.
I'd never come across one of these bus gates before (I was born and bred in London) so hadn't realised what it meant. It seems I'm not alone, a quick google search highlights that a great many people have been caught by these , the signs are not at all clear, and unless you've re-read the highway code recently you probably wouldn't know what a light blue circle with a white single decker bus means anyway?
They are legal but are a big money maker for local councils, one reportedly earning over £400,000 already!
You have been warned.