Appealing at a late date ?

From the website linked to, the camera takes three pictures in a defined short space of time, so the evidence from the camera could show the distance travelled in the bus lane.

It's not relevant to the OP's question however; AFAICT there is no national rule or law covering driving in a bus lane for a short distance, only local guidance. The quoted 20m figure is not from the area where the OP committed the offence.

Chris

I'd hope there'd be a bit of common sense when enforcing the regulation. If the road became blocked because of an accident, say, except for the bus lane, would you think it ok for people to be fined to use it just to bypass that holdup? Which would be a different scenario from using an active bus lane to bypass a traffic queue.

Me too, but sadly that isn't often the case with these things!

I'd imagine if the cameras were active, FPN's would be issued that you would then need to appeal. In theory, you would presumably still be committing an offence however.

Chris

If the camera takes a series of pics it should show just how long you stay in the lane - or rather show if you leave it as soon as possible.

Yeah, right. You're a motorist and therefore guilty.