The Nazi concentration camp survivor Manfred Goldberg was 84 when David Cameron promised a British memorial to the Holocaust. “Last month I celebrated my 93rd birthday and I pray to be able to attend the opening of this important project,” he says on the government website. That day has been put still further off by a procedural hitch in plans to amend a 1900 act that forbids buildings on its proposed site, Victoria Tower Gardens, a public park just up the Thames from the Palace of Westminster. It is heartbreaking that few survivors may live to see the memorial’s completion,...