I agree, it seems odd that C4 news, who are probably the best at investigative reporting on British TV didn't pick it up, they described him as a businessman, which is most likely true, but a quick google leads you to his agent, IMDB, equity membership etc.
I'm not saying C4 were complicit in anything, but they were sloppy in their due diligence. Had they introduced him as "Businessman and bit part actor" then it would be transparent.
I'm still curious as to why he seemed to be in character rather than himself, its odd - this of course doesn't effect the other idiots C4 filmed.
However I do agree with them on one point, that police cars should not be decorated to promote any group or cause, they should be decalled uniformly as police cars, nothing else.