I was driving along the M4 this morning, about 11am. Two lane traffic.
I was in lane 2, and was approaching a tiny black Citroen C2. It was doing a really annoying speed of about 66mph, and wasn't making much progress towards overtaking anything. It had a clear, sufficient gap in lane one to move over - but it would not budge over to let me by.
Keeping a good distance - I gave a brief light flash. He looked in his mirror and saw it, but still didn't move over.
To cut a long story short, he seemed to be refusing to move over (I had a que of cars behind me also wanting to pass him).
I must hold up my hand to the fact that I was getting a little bit frustrated. I ended up getting far too close to the citroen - probably in the realms of tailgaiting. I gave a couple more light flashes which the driver saw, and made a (friendly) hand gesture that I wanted to pass.
All I was greeted by was a dab on his brakes, and again refusal to move to lane 1.
At one point he made as if he was going to move over, but then changed his mind, causing me to have to ease off, after preparing to pass him.
When he finally did move over, and I passed him, I was rather horrified. In the little Citroen, was the unmistaken presence of two uniformed police officers. And I had been effectively trying to "encourage" them out of my way for about 3 miles

The officer made a very clear hand signal to me that he was furious, and as I pulled back in front he flashed his headlights at me. Being in a personal car I guess he couldn't pull me over, but still, I expect he noted the VRM, and I'm really not looking forward to any consequenses.
I'm not sure exactly what they can do when not in the "works" vehicle, but I'm guessing someone will pay me a visit very soon.
Bottom line is, I shouldn't have got so close behind it, and I hold my hand up to that. And I know it's not a valid defence, but I would expect a police officer to drive in such a manner that doesn't confuse and impede the progress of motorway traffic

Any thoughts on how this might pan out, would be interesting :-/