Originally Posted by
treadigraph
My only immediate reference are some 1/48 kits, Mk1, MkIX and MkXVI, and a Seafire XV, all of which have them marked, looks like they are held in place by screws or dzus fasteners.
For example:
I have to admit I've never noticed them on a real Spitfire (or on my Airfix 1/72 Spit many years ago) so I suspect they were extremely well-fitting and therefore almost invisible under a couple of coats of Grey or Sky, as the case may be.