Well done! It's good to have a mystery solved.
I need to make a correction to what i said myself. Looking at the yellow/pink bit, it's not the result of silver chloride,
that's the result of silver NITRATE.
I've been in discussion with somebody from Malta who confirmed that.
I'd been led a little astray by the Mdina book, which refers mostly to silver chloride, but that acts differently to silver nitrate, which was in use, I believe, far more.