"When is a person dead?" hardly seems an unreasonable question in a medicine interview.
The Blair question is, I think, a brilliant one, being open ended enough to get a candidate talking about all the 19th century politicians they know whilst showing how much they know of current politics. Seems tough, but maybe they reserve it for people daft enough to apply to Cambridge for PPE!
In my subject, Maths, questions, even when ridiculous, tend not to make good soundbites because the general reader and/or journalist doesn't understand them and/or isn't interested. e.g. "here is a side of a4, prove the Riemann Hypothesis" might only generate a letter to the telegraph from candidate's agitated parents because the interviewer didn't say please and so fazed young Jonny/Jenny with their lack of manners.