Some people have an uncanny knack of being ‘in the room where it happened’, as Alexander Hamilton puts it in the eponymous musical. That certainly applied to Sir Alexander Cadogan, the Permanent Under Secretary (PUS – the top civil servant) at the British Foreign Office for eight turbulent years from 1938 to 1946. Although now a largely forgotten figure, he had greater influence on British foreign policy during the Second World War than many more famous names, and was one of the key architects of the post-war international order.

Cadogan’s official photograph captures the persona which he presented to the world: the ultimate civil servant, efficient, unflappable, shrewd and watchful. This is the Cadogan who earned the trust of three very different Prime Ministers (Chamberlain, Churchill and Attlee) and their Foreign Secretaries (Eden, Halifax and Bevin). But there is another Cadogan, the one he poured nightly into the diary which he kept from 1933 to the end of his life. This is full of sardonic wit and frank comments on the interplay of the big personalities he worked so closely with, their motives and (especially) their foibles.

So who was this diplomat with such powerful influence behind the scenes? Alec Cadogan was the youngest child of the fifth Earl of Cadogan and, as such, expected to earn his own living, even though the family had great wealth (owning a good chunk of Chelsea). After Eton and Oxford, Alec passed the Diplomatic Service Exams in 1908. Following stints in Constantinople and Vienna, he returned to the Foreign Office to deal with trade embargoes during the First World War. In 1923, he was made Head of the League of Nations Section, and spent the next decade making his reputation as the leading British expert on the affairs of the League. His experience of why it failed was to prove invaluable when it came to designing the United Nations.

By now one of the recognised stars in the Foreign Office galaxy, Cadogan was sent to China as the British Minister in 1934, giving him a familiarity with the Far East which would be useful in wartime policymaking. In 1936, he was summoned home by Anthony Eden, newly appointed as Foreign Secretary, to become the deputy to the then PUS, Sir Robert Vansittart.

Cadogan’s recall from Beijing was part of a plot by Eden, later supported by Chamberlain, to get rid of Vansittart. The latter’s dark forebodings as to Hitler’s eventual aims were prescient, but his style was so bombastic and verbose that that his arguments lost all impact on his ministers. Cadogan’s approach was very different: he worked hard, mastered the detail, analysed clearly and produced concise and balanced advice. Cadogan (who replaced Vansittart as PUS in early 1938) was however no apostle of appeasement. His diary shows that as the Munich process developed, he became ‘completely horrified’ at the concessions Chamberlain was proposing to make to Hitler over Czechoslovakia. He gave Halifax ‘a piece of my mind’. This evidently shook Halifax who, after a sleepless night, turned against Chamberlain’s approach and began to work for a harder-edged strategy. Cadogan had achieved what Vansittart never could: real influence on policy.

The outbreak of war meant an even more crushing workload for Cadogan as he led the Foreign Office in adapting to the new reality. In Whitehall, a whole bureaucracy of war sprang up, and Cadogan spent much energy trying to get some semblance of coordination in the overseas activities of the Ministry of Economic Warfare, the Political Warfare Executive and the Special Operations Executive (instructed by Churchill to ‘set Europe ablaze’). As German forces occupied more European countries, governments-in-exile set up shop in London. All had their demands and their sensitivities, none more so than de Gaulle, who taxed Cadogan’s legendary patience to the limit.

The advent of Churchill in May 1940 had major implications for Cadogan. Churchill rapidly came to appreciate this super-competent operator who produced solutions to his problems. Cadogan was soon attending all the meetings of the War Cabinet. These were typically held late in the evening and dragged on interminably. Churchill and the Chief of the Imperial General Staff General, Sir Alan Brooke would have furious rows. Cadogan was equally fearless in standing up to Churchill when necessary. But he preferred to keep a lower profile, letting  ministers argue about foreign policy and making sure he was tasked with the follow up. Labouring deep into the night, he would reconcile the arguments around the Cabinet table, often in the form of a message from the Prime Minister to Roosevelt or Stalin. It helped that Cadogan developed an uncanny ability to imitate Churchill’s writing style. The next morning, after clearing lines with Eden (who had become Foreign Secretary in late 1940), he would take his draft back to Churchill, who might still be in bed, dictating to a secretary. The storm clouds of the previous night would have cleared and the Prime Minister would sign off Cadogan’s proposals with barely a glance.

The rapport which Cadogan struck up with Churchill was the source of his great influence. But it created a real problem which he never overcame. Cadogan became in practice the chief diplomatic adviser to both Churchill and Eden, while at the same time trying to oversee the entire work of the Foreign Office. By tradition, all advice from FO officials to the Foreign Secretary passed through the PUS. Cadogan would often spend hours each day in War Cabinets and Churchill’s meetings with foreign visitors. Because he was the only senior official in the room where it happened, he would then spend further time dictating telegrams and records. While he was on this treadmill, the work of the Foreign Office destined for Eden piled up on his desk. He never managed to reform office procedures to reduce the load of paper. Delegating was not his forte. But however hard-pressed he was, he always had something of value to add, as the eminent historian Sir Llewellyn Woodward (who spent years trawling through the files for his ‘Official History of British Foreign Policy in the Second World War’) observed:

‘Sir A Cadogan had remarkable powers of judgement and lucid expression. His minutes on paper after paper deal with almost every aspect of foreign affairs. … They often have a certain irony, never any rancour or prejudice. Only their modesty is delusive and the reader of these short notes written … in a firm, quiet hand may not realise at once how great a mastery they show’.

At weekends, Cadogan suffered particularly from his burden of being the indispensable man. If Churchill was at Chequers and Eden at his country house at Binderton in Hampshire, Cadogan felt obliged to stay in London. A crisis would flare up, telegrams would flow in, Cadogan would go into the office and prepare advice on what should be done. He would then send despatch riders off to his far-flung political masters with the papers, and wait for his telephone to start ringing. Or, worse still, ministers would start to think for themselves:

‘These weekends are awful. Ministers get time to ‘think’, which I think they do on country walks, in the course of which they lash themselves into a frenzy about nothing much. Then, on returning home, they seize the telephone receiver like a drunkard seizes the bottle, and the whole place flares up. … And the PM sits somewhere in the country, like a spider in the middle of his web, and tickles all up’.

Churchill rated Cadogan so highly that he insisted on taking him to all the main wartime summits. Cadogan earned his spurs at the first of these, the Churchill/Roosevelt meeting at Placentia Bay, Canada in August 1941. Roosevelt unexpectedly asked the British side to draft a declaration of principles which would underpin the approach of the two countries to the post-war world. Churchill turned to Cadogan, who set to and wrote out from scratch the first version of what became, after some amendment, the Atlantic Charter. One of its most significant proposals was for a ‘wider and permanent system of international security’, laying the foundation for the United Nations. On the way home, Churchill said to Cadogan ‘Thank God I brought you with me!’ Cadogan went on to participate in the great three-power summits in Teheran, Yalta and Potsdam. In Yalta, he and Churchill pressed strongly for France to be given a permanent seat on the UN Security Council: for this, Cadogan surely deserves a small statue in front of the Quai d’Orsay in Paris. In Potsdam in July 1945, Cadogan waved off Churchill and Eden as they went home for the outcome of the general election, and was at the airport to greet the new team of Attlee and Bevin.

Having signed up the Americans in the Atlantic Charter to the idea of an improved system of international security to replace the League of Nations, Cadogan put some of the Foreign Office’s best brains on to developing detailed proposals so that Britain could make a major contribution to shaping the UN Charter. Cadogan led the UK delegation to the Dumbarton Oaks preparatory Conference in 1944 and played a leading part in the final negotiations in San Francisco leading up to the adoption of the UN Charter in June 1945.  It was therefore fitting that Bevin asked Cadogan in 1946 to become the UK’s first Permanent Representative to the UN in New York. After retirement in 1950, Cadogan remained active well into his 70s, including a spell as Chairman of the BBC. He died aged 83 in 1968.

What lessons can Cadogan’s career offer to those interested in reinvigorating the rules-based order he was so instrumental in creating? I would suggest two. First, changing the structure of international relations needs a combination of vision (such as that set out in the Atlantic Charter) and the hard work and pragmatism to turn these into workable institutions. Second the crucial importance of alliances. Cadogan was the Foreign Office’s leading multilateralist. He spent his formative years struggling to make the League of Nations work. Most of his energies during the war went on consolidating partnerships with the US, the dominions and the governments-in-exile,  and recruiting neutral countries to the cause wherever possible. Cadogan saw that it was vital that Britain should be at the centre of a dense web of international connections if it was to help shape the future.