jno, I used to administer that test. Almost everybody, even those with quite bad damage knew Mrs Thatcher, then John Major took over and scores dropped amazingly! I am retired and not good at knowing the time as i no longer wear a watch and its not that important, ditto, day of the week.
If you are concerned, don't try and diagnose your friend yourself, get the person to see a doctor. That kind of word mix up, especially if it is of recent sudden onset says vascular insult (mini stroke) or intracranial pressure issue rather than alzheimers.