The answer to the question of what to do on HS2 (Nils Pratley on finance, 7 October) depends on the opportunity cost. Everything that can be done is affordable, but if the Treasury insists that the price of more for HS2 is child poverty, cold pensioners, unbuilt hospitals and more obstacles to compensation for victims of injustice (Chagos, contaminated blood, post office, Grenfell etc) then HS2 must stop at Old Oak Common. A sculpture called Black Hole by Anish Kapoor could be built there as a monument to Treasury orthodoxy. Roger Steer Sheffield Shira Rüb suggests that putting oestrogen in the water will stop all wars (Letters, 7 October). Sexist claptrap. There have been plenty of wars started by women: Margaret Thatcher, Golda Meir, Indira Gandhi, Elizabeth I, Cleopatra. When women get into power, they are just as likely to go to war as men. Paul Whiteley Bittaford, Devon James Cleverly out (Labour and Lib Dems gleeful as Badenoch to face Jenrick in Tory leadership race, 9 October)! A victim of a Keith Flett jinx (Letters, 8 October)? Jude Carr London So, it’s Badenoch versus Jenrick. Is this the evil of two lessers? Philip Lidster Wolverhampton Keir Starmer has achieved the unimaginable feat of making Jeremy Corbyn look like a safe pair of hands (Marina Hyde, 8 October). Michael Heaton Warminster, Wiltshire Is it too early to start a Labour party leadership contest? Paul Morrison Derry