Who was Emma Hamilton? Ruthless chancer, victim of society’s double standards or both of the above? If you are not up to speed on this discarded figure of Georgian society — best known as the mistress of Horatio Nelson — April De Angelis’s new play will certainly fill you in. In fact, the first half is so dense with Hamilton and her mother, Mrs Cadogan, reminding each other about their biographies that there is little room for drama amid all this sparky exposition.