Ha! just taken mine apart: trim off, assembly unplugged, unsrewed, taken inside. Solenoid is stuck in "open" position and won't allow catch to engage and lock shut. Solenoid unscrewed from assembly and treated to mild swearing and an inquisitive knife blade. Prising action on one corner releases stuckness and actuator whirrs back out to shutting position.
Pushed it in and out a few times: apparently not stuck any more!
All now back on the car and working fine. Left the trim off for now and the toolkit in the car, just in case!
Will look around for a spare from a scrappies too.
mi@k: cheers for the email, and cheers for the impetus to get it sorted!