To make Gannet (252) as original as possible I wonder what the original liners for the transom bung drain holes were made from.  They look copper of course but they also are not just a simple copper tube insert. And where to get them? All plastic nowadays but they just don't seem to look the part on a 1951 boat with no transom flaps.  Any ideas guys?

Make some from suitable i/d copper tube. Anneal it first, use a lump of hardwood drilled to accept the tube and practice your copper beating skills to create a neat flange. Yes, easier said than done, but agree that they should not be plastic. good luck

Ronstan do some which are chromed brass. One has metal liner with a plastic screw plug and another is all chromed brass but the plug is slotted for a screwdriver (or 10p!).

Not exactly right but a step closer to original than plastic...

part numbers RF737 and RF734  (24mm hole diameter)