It was a risk, going home for dinner at such a time, but the sense of filial duty beats strongly in these veins. We sat in silent apprehension, eating our pasta in small, cautious bites, until Mum spoke at last. "What," she said apparently casually, "do you think of Tesco changing its '10 Items Or Less' sign?" Dad put down his knife and fork, and pushed them together. The tiny clink rang out as an unmistakable declaration of the opening of Round 62,237 of this recurring fight.