[Lynn Eades]

Hi Rob, The spring is definitely a replacement.
I had 4 originals.
One i traded of to Nigel Ward in Australia. he made about 20 copies if I recall correctly. He took them to the U.K to sell.
Yes they have two pinning holes and above that is a smaller drain hole.
The original spring only has an air gap about the same size as the wire dia. (do you follow?} One I have appears to have a slightly lighter spring.
The inner tube is marked TL12433 FAACO 42
The tubes seem to be stainless and have no primer only an olivey green paint
In contast, he cast top is marked FMCo and has a smaller i.d. to the B.G. mounting hole, than your one pictured.
Your screw has probably been replaced. One i have is much shorter, but the same head style.
Of the four, the one Nigel had, had a pitted top casting. The three I kept being better. One I have has very faint markings.
The flange on the bottom is marked TL12429 around the big dia.
The outer tube is marked again with the FAACO (Ford Anti Aircraft Co?????)
but the part number is faint. One, I cannot find any markings.
Does that help?
I'd say the main bits you have are original, if you can forgive the hole size in the top casting and the keeper and screw.
The bottom bit looks rather new?
It is likely the keeper is hand finished, in keeping with British methodology