The first Hudsons were shipped to Liverpool in February of 1939. The Hudson Mk.I entered service with the No.224 Squadron of the RAF's Coastal Command at Gosport in the summer of 1939. By the time that war began in September of 1939, the Hudson Mk.I was also serving with No.233 Squadron, whereas Hudson Mk.IIIs were in the process of replacing the Avro Ansons that were serving with No.220 Squadron. The pilots of No.224 Squadron's Hudsons were the first RAF pilots to exchange shots with the Luftwaffe, which took place on the war's second day. On October 8, 1939, a 224 Squadron Hudson became the first aircraft of American design to destroy an enemy aircraft, when a Dornier Do 18D flying boat was destroyed off Jutland. Four months later, a Hudson Mk.III of No.220 squadron participated in helping to direct HMS Cossack in the boarding and seizing of the Kriegsmarine prison ship Altmark in Norwegian waters.
Antisubmarine patrol became the primary Hudson mission. During the first years of the war, the three original Coastal Command Hudson squadrons were joined by Nos.206 and 269 Squadrons. The Hudsons flew regular maritime patrols and anti-shipping sorties. In early 1940, many Hudsons had air-to-surface ASV Mark I radar sets installed, which increased their effectivenes.. They were active in the Norwegian campaign of April-June 1940 and they were important in covering the withdrawal of Allied troops from Dunkirk. Hudsons also served with No.2 Camouflage Unite during 1939-40, and from
July 1940 onward with No.1. Photographic Reconnaissance Unit. They flew low-level and bad-weather sorties over Germany and occupied Europe. One RAF Hudson was assigned a cover clvil regiatration of G-AGAR and flew covert missions over Baku and Batumi in the USSR out of RAF Habbaniyeh in Iraq.
Hudsons were operated in the anti-submarine role by the RAF beginning in August of 1940. Detachments from several squadrons flew out of Aldergrove in Northern Ireland to cover the Western Approaches. Seven months later, a detachment from No.269 Squadron began antisubmarine patrols from Kaldardanes in Iceland. On August 27, 1941, one of the 269 Squadron Hudsons, under the command of Sqdn.Ldr. J. H. Thompson damaged the sufaced U-570, which was forced to surrender, becoming the first U-boat captured by the RAF. Later, after the US had entered the war against Germany, RAF Hudsons flew out of NAS Quonset Point in Rhode Island, out of Waller Field in the British West Indies, out of NAS Norfolk in Virginia, out of Gibraltar, out of North Africa, out of Lydda in Palestine, and from Sicily, Italy and Corsica.
RAF Hudsons also flew convoy escort, maritime reconnaissance, and also flew occasional bombing sorties. 35 Hudsons of Nos 59, 206, and 224 Squadrons pqrticipated in the second 1000-bomber raid against Germany on the night of June 25/25, 1942. The Hudson was also used as a bomber in the Far East, beginning in early 1942 with No. 62 swuadron in Malaya, and in this theatre it also served with Nos.139, 194, 217, 353 and 357 Squadrons in the bombing, convoy escort, and supply dropping roles.
Production of the Hudson ended in May of 1943, after 2941 examples had been built. By this time, the Hudson had become increasingly obsolete, and was largely superseded by later types in its primary role of maritime reconnaissance. The Hudson then moved into secondary roles such as meteorlogical flights, air-sea rescue (for which it carried a Mark I airborne lifeboat underneath the fuselage), the fropping of agents into enemy-occupied territory, training, and transport work. The Hudson was also operated bo BOAC in support of the Atlantic Ferry, and from November 1940, Hudsons were flown across the Atlantic rather than being shipped by sea. The last Hudson was retired from RAF service in April 1945, when No.251 Squadron transitioned to Fortresses.