As a Golden Age of Detection fanatic, me reviewing a modern crime novel is a bit like a velociraptor reviewing an iPhone. But Elly Griffiths' The Postscript Murders has a stronger than usual connection to the Golden Age.The story starts with the death of Peggy Smith, ninety-year-old resident of the Seaview Apartments in Shoreham on Sea. Her carer, Natalka, thinks she was murdered, and through force of personality manages to convince DS Harbinder Kaur, Peggy's neighbour Edwin, and the owner of a local cafe,…