It is Mummy’s 39th birthday. She is staring down the barrel of a future of people asking if she wants to come to their advanced yoga classes, and polite book clubs where everyone claims to be tiddly after a glass of Pinot Grigio and says things like ‘Oooh gosh, are you having another glass?’ But Mummy does not want to go quietly into that good night of women with sensible haircuts who ‘live for their children’ and stand in the playground trying to trump.