for a reason which escapes me, the UK FTO instructor regards himself as PIC, even if the LHS occupant holds an FAA PPL/IR or CPL/IR and can thus be legally PIC
If you are receiving Flight Instruction for a new rating, you are acting under the direction of an Instructor and therefore not technically in command. In most cases you would not have a valid rating to be IFR (Flying a N reg is an exception) JAR-FCL 1080
(c) Logging of time
(1) Pilot-in-command flight time
(i) The holder of a licence may
log as pilot-in-command time all of the
flight time during which he is the pilot in-
command.
(iii) The holder of an instructor
rating may log as pilot-in-command all
flight time during which he acts as an
instructor in an aeroplane.