Before I went to a dinner party in Kensington last week, "Do not mention the B word!" in the posh parts of London, it is perfectly fine to discuss sex and religion. But the subject that must be avoided at all costs is Brexit.

London is the second most pro-Remain region in the UK after Scotland. We London Leavers swap stories about friends who, on discovering our views, have dropped us or been angry with us. Many of you have decided to keep quiet about our opinions on avoid confrontation or scorn. We are the hidden Leavers. We quietly know and recognize each other as members of a persecuted sect.

But there are more than you could think. The proportion …