I was just thinking how easy it would be to persuade someone that they are going mad / senile even if they weren't. I'm sure it's the sort of thing that awful people in novels or films do to their parents in order to get their hands on the dosh. Such an easy way to mentally torture somebody by sewing seeds of doubt in their mind.
Mr H and I sometimes have disagreements about what we have told each other, or accuse each other of remembering something wrongly. We are both convinced that we are remembering correctly, although it cannot possibly be the case (and it's not in writing so neither of us can prove it).
Right now I am hesitating about passing on some casual news in case he says "I told you all about that the other week, don't you listen to a word I say?" I'm wracking my brain in advance and I don't recall knowing anything about it... aaggghh I'll just have to risk it! ;-)