Arrests etc
Hello GlueBall... Actually you just might have that happen. Not in London but a real possibility in the Schengen convention countries. Schengen convention dictates extensive co-operation between law enforcement agencies in serious crimes and does allow for example Italian officers making an arrest of Italian citizens in say Brussels.
I guess your point was that FAA has no jurisdiction over A British registered and operated aircraft over Africa. In this you are absolutely 100% right.
Cheers
JJ