When my sister-in-law S McC burst into tears, I thought that she must have overheard me criticise elements of the party as ‘rather common’.

In fact, when I had been waving my arms around to make my point, my long fingernails had scraped across her face. Blood was now gushing from a deep, three inch long, wound over her forehead.

This was bound to heal into a Harry Potter scar, for which I would be blamed forevermore.