History: When Joachim von Ribbentrop, soon to be appointed Germany's ambassador to London, visited Mount Stewart at Whitsuntide, 1936, Lord Londonderry took him off to Scrabo links course for a round of golf.
The result of the game is not known, but Londonderry's diplomatic skills must have been sorely tested by the fact that Ribbentrop was a terrible player. (Shortly afterwards, the German contrived to lose to a man who had not played a round for 30 years, having lost his arm to a lion while hunting in Africa.) After the match, Ribbentrop generously tipped his caddy half a crown. No sooner had the man received his gratuity than Londonderry snatched it out of his palm, saying it was far too much, and replaced it with a shilling. History was never going to be kind to a character whose instincts were less generous than those of a Nazi war criminal.
"Charley" Londonderry was raised to think of wealth, power and position as a birthright. He owned 27,000 acres in Ireland, and another 23,000 in England. His rental income was in the region of £100,000 a year - vast millions in today's money - and was supplemented by huge earnings from coalfields in Durham. Money and privilege he took for granted. What Charley wanted most from life was to match the achievements of his illustrious ancestor, Lord Castlereagh, who as British foreign secretary had dominated the Congress of Vienna in 1815. Throughout the 1920s he hosted night after night of grand political parties at his magnificent Park Lane house until finally, in 1931, he was made Air Secretary with responsibility for the RAF.
"One can't use a man's hospitality and not give him a job if he wants it," acidly observed a fellow Conservative.
Londonderry proved inept. His instincts were right - rearm quickly in the face of renewed German vigour - but he lacked the political skills to win over colleagues. In 1935, he was humiliatingly sacked from cabinet posts not once, but twice. He travelled immediately afterwards to Germany, where Nazi leaders, including Hitler, laid on red-carpet treatment.
Sir Ian Kershaw's brilliantly told story of Lord Londonderry's infatuation with the Nazis is another triumph for the acclaimed biographer of Hitler. This fascinating tale - Londonderry air secretary to Londonderry Aryan - is carried off with Kershaw's trademark of great learning worn lightly. The crux of the book is why a man who for years had been arguing so strongly that Britain must face up to the Nazi threat through a massive programme of rearmament would subsequently advocate "making friends with Hitler". The answer, says Kershaw, is compellingly human and personal.
"Humiliated at home, he felt esteemed abroad," he writes. "His searing resentment at his treatment by [prime minister] Baldwin and flattery at his reception by Hitler fuelled a sense that, liberated from the shackles of cabinet office, he could succeed where the Foreign Office professionals had failed."
In the years immediately before the second World War, Londonderry became one of the most prominent and vocal friends of Germany in Britain. The common perception was that he was Nazi. Or, as the Daily Express put it, that there was a "swastika over Ulster".
Ian Kershaw is not unsympathetic to Londonderry, who was never a traitor, yet he resists the temptation to regard him in a sentimental fashion. Londonderry did not share the Nazi preoccupation with race, but, his son wrote later, part of the attraction of Nazism was "its anti-Jew and anti-Russia character and its impatience at the dilatoriness of democracy". It is difficult to avoid the conclusion that much of that appeal was rooted in Londonderry's disdain for the modern political settlement which had supplanted so many of his class, who had governed for centuries.
After the outbreak of war in 1939, Londonderry was vilified. There was even talk of internment. He closed down the house in London to retreat in despair to Mount Stewart. A series of strokes left him barely able to write or speak. Yet even at the end he would not admit to an error of judgement. Instead he railed against the "useless" mediocrities who had conspired against him.
"I now see why I failed to understand the very second-class people I had to deal with," he wrote bitterly, "and how glad they must have been to get me out of the way."
Kershaw's conclusion is rather different. Londonderry, he writes, "was at so many junctures his own worst enemy - unable to let sleeping dogs lie, unable to avoid an ill-judged rejoinder to a perceived slight, unable to realise when it was better to keep quiet than to speak out, unable to acknowledge his own past mistakes, unable to recognise that continued fighting of old battles was unlikely to bring the vindication he so desperately desired, unable above all to see that sustained defence of his association with Nazi Germany rather than acceptance of an earlier flawed judgment shared with others was damaging to his cause".
Londonderry did not have it in his nature to admit that he had been wrong. Right up until his death he gave pride of place in his private library to a statuette of a helmeted SS man carrying a Nazi flag that had been given to him by Ribbentrop.
The National Trust, which now owns Mount Stewart, has kept this incongruous piece of Nazi memorabilia where Londonderry left it, a jarring presence amidst the beauty of that house and gardens on the calm shores of Strangford Lough.
Making Friends with Hitler: Lord Londonderry and Britain's Road to War by Ian Kershaw Penguin/Allen Lane, 488pp. £20