Before someone you know gets seriously ill, you tend to think that medicine consists of absolutes. Right answers. Perfect prescriptions. Broken bones fused so you never feel a twinge. But since my dad developed vascular dementia, I’ve realised that opinions differ, mistakes are made. Sometimes you have to decide yourself what might be for the best.

There are so many grey areas; you long for certainties, branches to cling on to. Take Dad’s diagnosis, for example. We all knew something was wrong. His short-term memory was shot. He flanked any conversation with bizarre non-sequiturs. He kept losing his car, taking the hinges off doors and dismantling appliances at night in the house where he lived alone. He’d leave 10 rambling messages in a row on our mobiles and then cheerily ring again, as if for the first time.

Yet getting the medical authorities to concede there really was something going on was nigh on impossible.