I had glued the companionway sill in place several days before, but the epoxy resin was still soft and sticky and had obviously not cured.
Reasoning that if it had not cured by now it never would, I removed the clamps. This is what it looked like.
Yuk. The front and port side pieces came away, although the starboard side piece was fine.
I glued the latter with a second batch of resin, so there was obviously something wrong with the first one. I must have made it incorrectly, but have no idea what I did wrong.
I briefly considered classifying this as a Cock Up, but it's no big deal really and so a Silly Error it is.
Such are the vagaries of epoxy resin ...
This epoxy is solvent free and cleans up easily with hot soapy water, so plenty of elbow grease and a scraper restored the cabin roof to bare deck.
When it was dry I refitted the pieces of sill, as here.
This cured overnight so no repeat of whatever I did wrong!