Vsf,
Missed your reply before editing, so I'm in the dark as to your post. All points of view are valid.
sting load,
Thanks for that. Seems they are crew unless they are about to cost someone a lot of money. It is true that the CAA regard th police observer as pax, simply because thy are not licensed. That really has no bearing on the case, as, as you point out, they are the sole reason for the thing getting airborne at all.
Ally,
Thanks for the input. Indeed some aircraft are not owned and operated by the police, and that is how, in the Strathclyde case, it was decided that the Warsaw Convention did apply because the aircraft was hired on an ad hoc basis from a commercial operator using a commercial AOC. In the EMASU case, the same argument seems somewhat strained, as G-EMAU was owned by the three constabularies and operated under a PAOC.
As you say, it will probably have to be dragged through the courts, taking time and leaving the injured party with no income, already three years down the line.
Natural justice says to me that the man was a member of the crew, and should be compensated as such.