DamienB - you say they are different, but according to John Farley's 2000 Lecture, intake design was changed twice during the development of the Harrier from the Kestrel.
Farley says "The intake design was changed twice in the pursuit of better specific air range in the cruise allied with good high altitude handling, without prejudice to the hovering performance. First 12 and then 16 auxiliary intake doors were fitted round the intake lip and also various boundary bleed door configurations were flown. The reaction controls were refined and to add a bit of polish to the V/STOL handling a new low authority pitch and roll autostabiliser was developed." http://www.harrier.org.uk/history/history_farley.htm
This fuselage has 12 doors so could be a hybrid/development of the P1127 (RAF), like the Plastic Pig. Don't think its XS694, damage shown in 'demobbed' photo isn't present on this particular fuselage, in fact the windscreen is intake, but taped.
Hopefully we'll get to the bottom of this particular jet
I'm with Xplumber on this, a testbed fuselage for some reason