36000
I was a controller & watch supervisor at Ramstein Radar Approach Control from Mar 77 to Mar 80. Once you got rated across the board (in all positions) you were a certified RAPCON rated controller (RAPC rating). If you got rated in the Tower it was a TWR rating.
Although the last National Serviceman is attributed to Lt Richard Vaughan RAPC who left the army on 13th or 16th May 1963, the true answer will probably never be known as there were as many as 50 national servicemen retained in BAOR until the end of that month. Their discharge being delayed because they were in hospital, in detention or for some other reason
Royal Army Pay Corps (RAPC) is one group that has this motto. it is also found on the watts family crest, among others. It is also the motto on the Distinctive Insignia developed for the 93rd Evacuation Hospital, approved 3 March 1942. The 93rd was involved in eight campaigns in World War 2; Sicily, Naples-Foggia, Anzio, Rome-Arno, Southern France, Rhineland, Ardennes-Alsace, and Central Europe. They also deployed to Vietnam, Saudi Arabia, and Kuwait.