Until recently, we'd never quite "got" sandwiches in the way Americans did. In the US, sandwiches are capacious parcels of pleasure. New Yorkers will cross town in their lunch hour to eat the perfect salt beef on rye. London sandwiches, by contrast, have often been sad affairs: cold, pleasureless morsels, to be dispatched, one-handed, as quickly as possible while staring at a screen. Our favourite national sandwich is still the sorry "sand-wedge", moist triangles available from chill cabinets in every supermarket in every high street.