You might remember a flurry of news stories some years ago about red wine being good for you. But unlike most dodgy diet advice, this story has some basis in rigorous scientific research.

‘Are you sure it’s free wine?’ I ask my friend Lydia as we dash down the street. ‘Look, I told you it is,’ she snaps back. ‘It says so here.’ Lydia points at a message on her mobile screen which I can’t read because she’s walking so quickly. ‘Free wine! Free wine! Free wine!’ she barks. ‘Now can you please hurry, the thing starts at eight.’