GAR
This all relates to the fact that the UK did not sign up to the Schengen agreement, essentially the border controls that were supposed to dissapear as part of our membership of the EU didn't, and as a consequence, if you leave the UK FIR you must flight plan out, complete Schengen formalities at your remote destination (ie Land at a customs capable airfield at first landing outside UK FIR)and then with at least 12 hours notice inform the UK authorities about your return time and return airfield.This is so that a couple of overweight plods in cheap Matalan suits driving a really rubbish car can come along and rummage through your stuff Its a job I suppose!!