He was charged in relation to an arrest he made, which is very much in the course of his duties, but here's another example for you with more media coverage - http://www.independent.co.uk/news/uk/crime/armed-police-offi...

edit: you may also be interested in knowing where police get the legal right to break the speed limit, which is also obviously not from their non-existent immunity to the law:

> The Road Traffic Regulation Act 1984 and The Traffic Signs Regulations and General Directions 2016 exempt emergency vehicles from:

- observing speed limits

- observing keep left/right signs

- complying with traffic lights (including pedestrian controlled crossings).

http://www.app.college.police.uk/app-content/road-policing-2...