Deep inside 10 Downing Street on Jan. 31, Boris Johnson picked up a small, hand-held gong and beat it, on the stroke of 11 p.m. Surrounded by his closest aides and supporters, the British prime minister was marking a moment in history - the precise time at which the U.K. left the European Union after almost half a century of membership.

Re: “Fifty versions of the truth”, Letters, May 4.