51 M.U. began their work on the 1st August 1940 under the command of Wg/Cdr Hesketh and the establishment was 5 Officers, 76 Airmen and 20 Civilians. They received aircraft from the manufacturers and checked them over carrying out any modifications needed before delivery to Squadrons. These delivery flights were carried out by A.T.A. pilots many of whom were women. The first aircraft to arrive were Hurricanes, Ansons, and Oxfords followed in December by Beaufighters (See Links page), Bostons and Wellingtons. Their activities rapidly expanded and the satellite airfields of Blidworth and Hoar Cross were brought into use.
From 1943 51 M.U. were dealing with Typhoons, B-17ís, Liberators and Mosquitos, and towards the end of the war they were at their busiest receiving aircraft that had come to the end of their service for example 26 Whitleys which arrived at Hoar Cross in September 1944. The establishment had now risen to 21 Officers, 4 W.A.A.F Officers, 617 Airmen and 190 W.A.A.F.S and its stock of aircraft by July 1945 had risen to 780.
From 1946 they prepared Magisters for civilian use and Mosquitos for the Air Forces of France, Belgium, Czechoslovakia, Norway, Denmark, Sweden and Israel. (See Links page for more info on the Israeli Air Force)
By 1947 they had broken up 900 Typhoons, 500 Liberators, and 150 Fortresses and the Unit then began to decline in size. From June 1948 until March 1950 Oxfords arrived for preparation before being sold to Air Forces in the Middle East, and after 2 years of aircraft storage Runway 04/22 became available for normal use. In 1951 Lincolns were being kept in storage for readiness in any emergency (Operation Firedog in Malaya) and by 1953 the remaining 160 personnel were solely occupied with this task.
51 M.U. handled most of the aircraft flown in World War 11, they were the only Unit who served for the whole life of RAF Lichfield until its closure on the 15th April 1958.