10 Auster Air Observation Post (AOP) Mk5/Mk6 aircraft were inherited by Royal Pakistan Air Force (RPAF) at the time of Pakistan's independence in 1947. Auster AOP Mk5/Mk6 remained in service with Pakistan Air Force (PAF) till 1961. Here I would like to add that Royal Pakistan Air Force became Pakistan Air Force with Pakistan becoming republic on March 23, 1956.
Main difference between Auster AOP Mk 5 and Mk 6 was Mk 6's strengthened rear fuselage for installing third seat and lenghtened landing gear for providing clearance to bigger propeller.
In 1953, 15 Brand new Auster J/5F Aiglet aircraft were purchased for RPAF and these served PAF till 1963. Auster J/5F Aiglet was designed as aerobatic training aircraft, specifications have been posted by forum member
inducedrag.
From my collection, here's pre-delivery photo of RPAF Auster J/5F Aiglet (serial# W4104).

Royal Pakistan Air Force Auster J/5F Aiglet (serial# W4104) on a pre-delivery test flight. This particular aircraft crashed on December 22, 1956.
PAF operated Auster aircraft as Air Observation Post (AOP) and for liaison & communication flights. More info plus photos/paintings of PAF Auster aircraft can be found in books related to PAF history.
Pakistan Army Aviation operated 4 Auster aircraft from 1947 to 1956 and replaced them with Cessna L-19 Bird Dog.
Abbas