My dear old grandad thought he was Bonnie Prince Charlie when he was in a care home.
We knew he wasn't Bonnie Prince Charlie.
But to be sure, we did have a family discussion and decided that we would rely on the evidence of our eyes and the fact that he had always been happy to be Mr Alfred Tennyson of 10, Acacia Avenue up until this point.
It seemed very unlikely then that he had morphed into Bonnie Prince Charlie.
We didn't know how to address him. He wanted to be called The King over the Water and referred to as Your Royal Highness.
Anyway, we asked the staff and they told us that he would get very upset if we didn't do this.
So, as we didn't want him to be upset, we nodded and agreed he was Bonnie Prince Charlie.
Of course, he believed it and we played along with it.
One day though, he found his way into Buckingham Palace and threatened to oust the usurper. People tried to blame us, his family, for encouraging him in his belief that he was really Bonnie Prince Charlie.
Is this how we deal with men who think they are women? Nod along with it.
I suppose that would work until we find them in women's prisons, refuges, changing rooms, sports, etc.
But what will we do when that all gets a bit much-after all we nodded along until we discovered it was too late and the genie can't be put back in the bottle.
Maybe we shouldn't have nodded along in the first place.