I spend most of my time drawing politicians, trying to work out what makes them distinctive. The eyes, the expression, their mood: it’s all about finding people’s peculiarities and accentuating them. When I started, I’d focus on the face. Everything else was an afterthought. It wasn’t until I came across a drawing by the Norwegian cartoonist Finn Graff – a cartoon of Helmut Kohl, I think – that I realised what I had been missing.