Academics have decided that you stop being young at 35 – a recent milestone for The Telegraph’s Harry de Quetteville. Better fetch the pipe and slippers! Researchers at the University of Kent have carried out a survey which says you have officially hit middle age when you hit your middle thirties. Quetteville ponders this: “A moment's reflection reveals that this is not such a stunning revelation. In fact, turning to Psalm 90, we are reminded that: ‘The days of our years are threescore years and ten’. If we do, indeed, live until 70, then middle age is, quite precisely, 35. In other words, these well-funded, modern-day brains from Kent have proudly unveiled a statistic that Moses managed to put his finger on in the Bronze Age. It is galling none the less. I don't feel middle-aged, and (pints of Spitfire aside) I certainly don't act middle-aged. Puerile, in fact, is a description that many might apply. But that may be because, like a huge number of my associates, I haven't done many grown-up things. On the domestic front, I haven't got married and don't have children. I only managed to acquire a mortgage last year (at least that's a relationship that will last). These are the big social markers of youthful adulthood – and they keep getting pushed back.”