1919, 1920 and 1922. Irwin's personal bests were 4:33.8 in the mile (set in 1920), 15:15.6 in the three miles (set in 1919) and 15:17.8 in the 5000 metres (set at the 1920 Olympics). Military career Irwin joined the RNAS in 1915 and was entered as a Probationary Flight Sub-Lieutenant on 13 August of that year. He went on to command non-rigid airships of the SS Zero, Coastal and NS types "in Home Waters and the East Mediterranean" during 1916 and 1917 and was promoted to Flight Lieutenant with seniority 1 April 1917. At RNAS East Fortune, Scotland, he "enjoyed the reputation of having the smartest ship." Under the RAF, which subsumed the RNAS in 1918, he was granted a short-service commission as Flight Lieutenant on 24 October 1919. Irwin subsequently commanded the rigid R29, with Noël Atherstone, who would again be his second-in-command on R101, as his first officer. He became captain of the R36, by now regarded as a civil aircraft, in 1921. On the R36's 14 June 1921 trial flight, with journalists and Metropolitan Police representatives aboard, to assess the airship's value for road-traffic control during the Ascot Races, he served as an officer under Major George Herbert Scott (who had commanded the R34 on its Atlantic crossing in 1919 and was to become another victim of the R101 disaster) . On 21 June, however, Irwin and Scott were involved in an incident with the same ship when, approaching RNAS Pulham, Scott "took over from Lt Irwin and decided to direct the landing himself." An excessively rapid approach to the mooring mast led to a violent deceleration and accidental ballast release, causing a sudden pitch-up that badly damaged the ship's bow. Irwin "broke down" on seeing the scale of the damage. The accident was attributed to equipment failure, and the R36 never flew again (despite various proposals to recommission it), remaining in its hangar until broken up in June 1926. The episode was not the first landing accident in which Scott had been involved and foreshadowed several incidents involving the R101. Subsequently, Irwin became captain of the R80. Irwin held ground positions at RAF Headquarters (Coastal Area), at RAF Leuchars and with the Air Ministry's Director of Operations and Intelligence before his first transfer to the RAW in 1924. After being transferred back to the RAF (see below), he commanded the RAF School of Balloon Training at