The annual Christmas dinner with my former school friends beckons and I am full of trepidation. We’ve finally moved on from the boys throwing bread rolls at each other while the girls tut, only to reach the stage where people are getting married and talking about mortgages. How did I get from adolescence to middle age without noticing passing through adulthood? And then, of course, somebody asks me how work is going, so I tell them all about job applications and difficult cannulation and parents who threaten to stab you, and how sometimes I wonder if I could be replaced by a …