WE have a sense, a gut feeling if you like, that we know pain when it presents.

We recognise distress when we see it – in people and in animals that we know well. We can’t always describe it in objective terms, but we recognise it. Sometimes it’s just in the ‘pained’ look in his or her eye. He is, as has often been said to me, ‘off-colour’ or ‘just not herself’ today.