Lieutenant-General Sir Frank Noel Mason-MacFarlane, (23 October 1889 – 12 August 1953) was a senior British Army officer, administrator and politician who served as Governor of Gibraltar during the Second World War.

Early life and military career Frank Noel Mason was born on 23 October 1889, the son of a doctor. His father was convinced that war between Germany and Great Britain was inevitable and joined the Territorial Army to work as an army doctor. As a result, his father was frequently absent, and a major influence on him when growing up was a German governess hired by his father. Mason-MacFarlane was educated at Rugby School and, after attending the Royal Military Academy, Woolwich, was commissioned as a second lieutenant into the Royal Artillery in 1909. Until February 1909, his surname was Mason, but he hyphenated it that month to Mason-MacFarlane out of pride in his Scottish heritage as MacFarlane was the maiden name of his Scots mother.Butler, E.N. Mason-Mac, London: Macmillan, 1972 p.7

Mason-MacFarlane served in the First World War on the Western Front and in Mesopotamia. An intense individualist, Mason-MacFarlane's experience as a young artillery officer left him a reputation as an officer who was always ready to "look out for trouble" and who had a profound distrust of the higher command. A non-conformist, he was known for his love of amateur theatrical acting, sports and for writing sarcastic doggerel poems mocking the high command. In the winter of 1915–16, he served with the relief forces involved in the bloody fighting outside of Kut as the British sought to unsuccessfully rescue the Indian 6th Division besieged by the Ottomans inside Kut. He was awarded the Military Cross in 1916, a bar to the award in 1918 (gazetted in September) and a second Bar in the same year, awarded while he was attached to the Artillery Headquarters of the 41st Division, the most junior Kitchener's Army division. The citation for the second Bar was published in a supplement to the London Gazette on 2 December 1918, and reads:

Mason-MacFarlane was also awarded the French Croix de guerre and mentioned in despatches during the First World War.

Between the wars Between the wars, Mason-MacFarlane attended the Staff College, Quetta from 1919 to 1920. At Quetta, his evaluation upon graduation declared his ability as "above that of any of his fellow students", though his judgement was described as only "fairly good ... rather immature and lacking balance". Afterwards, he served on regimental duties, before attending the Imperial Defence College, a prestigious posting for the most promising officers, in 1935.Smart, p. 212 In 1931, after spending most of the preceding ten years in British India, he was appointed military attaché to Hungary, Austria and Switzerland. The director of M3, the intelligence section of the War Office dealing with Central Europe wrote in an evaluation of Mason-MacFarlane: "He combines a first-class brain with a remarkable flair for intelligence work. He has a keen sense of humour and is an excellent linguist. Full of mental and physical energy and with great initiative...he should go far". A lover of fast cars, he was badly injured in a car crash in 1933 that left him with spinal pain for the rest of his life. In 1934, Mason-MacFarlane returned to Great Britain.

Mason-MacFarlane served as Britain's military attaché to Berlin prior to the Second World War, under the ambassador Sir Nevile Henderson starting in January 1938. Additionally he served as military attaché to Hungary, Austria, Switzerland and Denmark. In his favourite Ford V-8 coupe, Mason-MacFarlane went out to personally observe the Anschluss after the Oberkommando der Wehrmacht denied to him that it was happening and to investigate the German-Czechoslovak border region during the May Crisis.Bouverie, Tim (2019). Appeasement: Chamberlain, Hitler, Churchill, and the Road to War (1 ed.). New York: Tim Duggan Books. pp. 179–180. . His reports during the May Crisis that he found no evidence of an imminent German invasion of Czechoslovakia did much to cool down the heated atmosphere during the weekend of 20–22 May 1938. "Mason-Mac" as he was known to his colleagues in the embassy in Berlin was viewed as an eccentric with some like Sir Walford Selby, the ambassador in Vienna, praising him for his "consistently good advice" while others like Sir Alexander Cadogan, the Permanent Undersecretary at the Foreign Office, regarded him as reckless and too easily excited.Neville, Peter Appeasing Hitler The Diplomacy of Sir Nevile Henderson, 1937–39 London: Macmillan, 1999 p.195 The British historian D. C. Watt called Mason-MacFarlane a "courageous eccentric" who very much wanted to assassinate Hitler.Watt, D.C. How War Came, London: Heinemann 1989 p.183.

On 27 July 1938, Mason-MacFarlane reported to Henderson that the Wehrmacht was preparing for a war against Czechoslovakia, stating in a report that the German Army generals were "seeing to it that if the emergency arises their preparations shall not be found wanting".Neville, Peter Appeasing Hitler The Diplomacy of Sir Nevile Henderson, 1937–39 London: Macmillan, 1999 p.89 Henderson passed on Mason-MacFarlane's report to London, but stated he did not believe that Hitler was preparing to invade Czechoslovakia. On 3 August 1938, Henderson reported to the Foreign Secretary, Lord Halifax that up to 8 German divisions had been sent to the German-Czechoslovak border, but he believed that this was a bluff on the part of Hitler to pressure President Edvard Beneš of Czechoslovakia to grant autonomy to the Sudetenland. In his own report, Mason-MacFarlane wrote the test mobilisations performed by the army were "desperately provocative. It is hard to see how Czechoslovakia can fail to mobilise in reply". Henderson sent Mason-MacFarlane to London the next day to "discuss the extent and significance of German military preparations". During his visit to London, Mason-MacFarlane met Lord Halifax; Sir Robert Vansittart, Chief Foreign Policy Adviser; and Sir Horace Wilson, Chief Industrial Adviser and a close friend of the Prime Minister Neville Chamberlain.Neville, Peter Appeasing Hitler The Diplomacy of Sir Nevile Henderson, 1937–39 London: Macmillan, 1999 p.196 Halifax wanted Mason-MacFarlane to take back a personal message to Hitler, a course of action which he rejected as a "waste of time".

During his time in London, Mason-MacFarlane made clear to both the Foreign Office and War Office his disagreements with Henderson, predicating that Germany was definitely preparing to invade Czechoslovakia that year.Neville, Peter Appeasing Hitler The Diplomacy of Sir Nevile Henderson, 1937–39 London: Macmillan, 1999 p.90 Upon his report to Berlin, on 8 August 1938, Mason-MacFarlane met Victor von Koerber, a retired officer and Berlin correspondent of the Wiener Journal, who had excellent contacts with the German General Staff. Koerber told him that Germany was going to invade Czechoslovakia in late September 1938. Koerber arrived unannounced at Mason-MacFarlane's office with his warnings that the General Staff were opposed to a war with Czechoslovakia and would very much welcome statements once again reciting London's willingness to defend Czechoslovakia. Mason-MacFarlane dismissed Koerber as an agent provocateur. The German General Staff, opposed to a "premature" world war, had sought to persuade Hitler to put off the invasion of Czechoslovakia under the grounds that it was likely to cause a world war before Germany was properly prepared. Unable to persuade Hitler, the General Staff had turned towards Britain as their best hope of stopping a "premature" world war. Mason-MacFarlane recognised he was being used as a pawn in an internal German policy dispute, writing "any bungling of an attempt to interfere from without with Germany's domestic politics during Hitler's lifetime would most assuredly lead to exactly what we all wished to avoid".

A week later, Mason-MacFarlane changed his mind, saying that British would not "be justified in supposing that Herr Hitler has made up his mind to go to war this autumn". Henderson believed that Hitler was bluffing, only seeking to pressure Czechoslovakia to change its policies towards the Sudeten Germans under the grounds the Germany was still not ready for the world war that was likely to result from an attack on Czechoslovakia while Mason-MacFarlane believed that Hitler was serious about war with Czechoslovakia sometime in the near future. Henderson in a dispatch to Lord Halifax stated that the two options open to Britain were either to repeat the warning of 21 May 1938 that Britain would go to war if Germany invaded Czechoslovakia or alternatively to pressure President Beneš to implement the conclusions of the Runciman Mission. Mason-MacFarlane preferred the former while Henderson preferred the latter. On 21 August 1938, Mason-MacFarlane met an agent of Colonel Hans Oster, the deputy chief of the Abwehr, who told him of Fall Grün (Case Green), the plan to invade Czechoslovakia.Wheeler-Bennett, John The Nemesis of Power, London: Macmillan, 1967 p.411. For the first time, Mason-MacFarlane learned that Hitler planned to invade Czechoslovakia on 1 October 1938 and of his belief that neither Britain nor France would do anything in the event of the invasion. Henderson in his comments on the report wrote that it was "clearly biased and largely propaganda".Wheeler-Bennett, John The Nemesis of Power, London: Macmillan, 1967 p.412. In late August, Mason-MacFarlane submitted a report to Henderson declaring that if Britain made an alliance with Czechoslovakia that this offered 'an outside possibility that we might avert or at any rate postpone catastrophe".

On 23 September 1938, the outcome of the Chamberlain-Hitler summit at Bad Godesberg ended with Hitler rejecting the Anglo-French plan for the cession of the Sudetenland as taking too long and demanded the region "go home to the Reich" immediately, a demand that Chamberlain in turn rejected. In the tense atmosphere with Germany and Britain on the verge of war, Wilson was left behind by Chamberlain in Berlin to try to keep the lines of communication open. Mason-MacFarlane was sent by Henderson and Wilson to deliver a message to text of Hitler's Bad Godesberg ultimatum to Prague but the German-Czechoslovak border was closed, forcing him to cross the frontier by a forest path. While crossing the frontier, he was caught up in the barbed wire, and a nervous young Czechoslovak Army soldier helped untangle him instead of challenging him, an experience that left with the conviction that Czech morale was poor. During his journey through the Sudetenland, he had to dodge bullets as he witnessed fighting between the Nazi Sudetendeutsches Freikorps and the Czechoslovak police and army.Butler, E.N. Mason-Mac, London: Macmillan, 1972 p.80-81