At a different time of year, our readers could be forgiven for thinking it was a Purim spiel, albeit a supremely distasteful one. David Irving, one of the world’s most outspoken Holocaust-deniers, was approached by Channel 4 to appear on the reality-TV show Celebrity Big Brother. Its producers interviewed him for some 90 minutes before deciding he was not quite suitable for the show. It remains unclear whether he was too controversial to appear — or not controversial enough.What is particularly alarming about this story is not just what it says about the nature of the modern “sleb”. On September 7, Irving appeared on a Radio 4 programme, The Reunion, which brought together some of those of those involved in the publication of the hoax Hitler Diaries in 1983. Irving appeared as “a historian” — a title unfortunately not prefixed with the rather more apt description “notorious Holocaust-denier”. Does this indicate a disturbing level of ignorance in the media about one of the vilest forms of modern antisemitism? Or is Irving now a mainstream public figure, by virtue — not in spite — of his notoriety? In a week when we witnessed something close to public hysteria in response to a puerile prank call made by TV presenters Jonathan Ross and Russell Brand to actor Andrew Sachs, perhaps we should be asking some rather more fundamental questions about the boundaries of acceptable discourse.