Talking to some English teachers about grammar and apostrophes, I was surprised to discover that they would mark "the princess's castle" (as in the castle belonging to the princess as wrong, and I was incorrect to claim it was OK to write this. It should according to them be "the princess' castle".
I would have said that either was acceptable but the extra, helpful s is preferable. In any case they said they would say it "the princess's castle" which makes no sense at all to me.
Bit depressed as these are people who will be teaching our children English....
I am right, surely? What do you all write for this? I used to be a journalist and have never worked on a newspaper or magazine that had no s as its style in these cases.
PS: St James's Park