Fide et fiducia is the motto of which group?

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.