In Christopher Hitchens article in The Atlantic titled "The Medals of His Defeats" a polemic against Churchill's reputation within the special relationship, he makes the following argument:
" Irving has a great facility for innuendo; its most successful application is the repeated suggestion that Churchill used his foreknowledge of German air raids sheerly for grandstanding purposes. On the nights when he knew that Göring's bombers would overfly London on their way to, say, Coventry, he would make a point of standing on the Air Ministry roof, or of taking a stroll in the Downing Street garden, thus impressing his staff and subordinates with his pluck and daring and sangfroid. On the nights when Enigma gave him private information about a raid on London itself, he would decamp to the country house of a wealthy friend. This accumulation of detail is so subversive of the legend as to make a greater difference in the mind of the reader than many more-serious shortcomings of generalship. The allegation has now been in print for fifteen years, and I have never seen it addressed by the Great Man's defenders, let alone rebutted."
The Irving he references here is David Irving. I don't need to give any details in a community of academic historians as to why the authorship automatically renders all points made at the very least spurious. This article is from 2002. So, is Hitchens right in his assertion that this point made by Irving has never been rebutted?
I'm not sure that is the most successful application of Irving's innuendo, it's not an allegation I've seen trotted out in the tediously frequent Churchill debates that veer between soundbites of hagiography and iconoclasm. From a quick dig around, the main extent of debate appears to have been a few letters to the Globe and Mail in 2000, starting with Irving:
"If I may respond, as a Churchill historian who has worked for 20 years on the great man's biography: It may well be, as Richard Langworth says (letter -- March 8), that Mr. Churchill spent many a night on the roof of No. 10 Downing Street.
As we now know, however, those nights on the roof were nights when Winston knew from codebreaking that London was not the target. When he knew that London was going to cop it, he hopped into his Daimler and had himself driven out to Dytchley, in Oxfordshire, for the night. Comparison of his desk diary, which I have, and the Air Ministry records indicate this beyond doubt. Of course, he was a magnificent orator. . . ."
It attracted a couple of responses, and some comment in the Churchill Society's Finest Hour (not the most impartial of sources, but then neither is Irving of course):
"Mr. Irving (we wrote) says he is a historian, but he is clearly unfamiliar with the function of Ditchley. Churchill went there not to avoid London, but to avoid Chequers (the official country house of Prime Ministers) when, on weekends of the full moon, Chequers could easily be spotted by enemy bombers. The PM explained that he did “not object to chance but feels it a mistake to be a victim of design.” (Fringes of Power, Colville, London: 1985, p. 263). Churchill visited Ditchley exactly seven times during the entire war. (Gilbert, Winston S. Churchill, vol. VI, London: 1983, passim.) Mr. Irving may like to know that the Luftwaffe visited London rather more frequently, and not just on weekends. "
Maybe Irving should have consulted one D. Irving's Churchill's War Volume One: The Struggle for Power:
October 1940: "[Churchill] returned reluctantly to Downing-street on the fourteenth. Dining that night in the fortified rooms, behind windows protected with steel shutters, he heard a bomb detonate in the Horse Guards Parade. On an instinct, he left the table and directed the cook and downstairs servants to the shelter. His secretary John Martin galloped down and jumped in on top of them just as a second bomb hit the treasury next door. (...) Standing on the roof that night, Churchill watched the fading dazzle of incendiaries replaced by the flicker of flames rising from Pall Mall and Piccadilly."
March 1941: "Five hundred planes attacked the Port of London that night. After dining at No. 10 with Harriman and Anthony Biddle, American ambassador to the governments in exile, Churchill handed out helmets and invited them to join him on the air ministry roof, climbing up through a manhole to watch the spectacle."
I mean, if he can't keep his own story straight then why should anyone else bother?