It is my understanding that:
"Authority of commander of an aircraft
141 - Every person in an aircraft must obey all lawful commands which the commander of that aircraft may give for the purpose of securing the safety of the aircraft and of persons or property carried in the aircraft, or the safety, efficiency or regularity of air navigation."
AND
"Acting in a disruptive manner
142 - A person must not while in an aircraft:
(a) use any threatening, abusive or insulting words towards a member of the crew of the aircraft;
(b) behave in a threatening, abusive, insulting or disorderly manner towards a
member of the crew of the aircraft; or
(c) intentionally interfere with the performance by a member of the crew of the aircraft of the crew member's duties."
Link:
http://www.caa.co.uk/docs/33/CAP393.pdf
In essence, a crew member who is PIC of a UK registered aircraft, not only has the authority to ensure flight safety, but would be
required to take action on any issue involving the aircraft's safety, whether this be a disruptive passenger, damage to property or indeed a police officer on the flight deck (which, in theory, could cause any PAX alarm, thus endangering the safety of the aircraft).
Just my twopenceworth
