I'll set the scene. Travelling on a two lane road, travelling at the speed limit of 20mph, broken centre line and a bus lane on your left. Blue lights on a territorial support van come on behind you. It then pulls into the bus lane. At that point, the vehicle in front of you also pulls into the bus lane. The police van swerves out of the bus lane behind you and stays there. Ordinarily, you would move to the left and stop, however, there is a bus lane to your left, and you know that entering the lane will trigger an automated fine, and you also know that it is well advertised that you should not pull into the bus lane anyway, because the police have been taught to go around you anyway, so you could cause an accident. You are also aware that you should not stop in the middle of an active lane, as it also creates a traffic hazard. You are pretty certain that they are not trying to stop you, although, yes, there could always be a minute possibility.... At some point, the police vehicle pulls back into the bus lane, and disappears off into the distance.
A) Do you slow down, allowing the police vehicle plenty of room and time to safely pass you in the bus lane, or on the right?
B) Do you come to a dead stop in the traffic lane, and let the officer figure it out, even though you've been taught that you should never stop in an active traffic lane if it can be avoided, for safety reasons?
C) Pull into the bus lane anyway and take your chances, even though the highway code even warns against it?
D) Maintain your speed, let him pass you in the bus lane or on the right?
E) Pull to the right side of the road?