RAF exchange pilots certainly got kills with the USAF in Korea. John Nicholls (later an AOC in C Strike or something equally important) got the first in December 1952 (after damaging three more).
Squadron leader Max Higson from No.43 Squadron destroyed at least one MiG-15.
A Flight Lieutenant Daniel who flew with 334 FIS at Kimpo was credited with damaging two MiGs during his six-month tour during 1952.
Flight Lieutenant RTF Dickinson, shot down one MiG-15
Flight Lieutenant John Granville-White shot down one MiG 15
Flight Lieutenant Graham S Hulse shot down three more MiG 15s
Other post war kills all happened in wars where admitting them was impossible or politically undesirable, in just the way that the SAS's exploits have so often gone unacknowledged.
I was assured (by someone who was there) that No.208 Squadron took its revenge after four of its unarmed Spits were downed by the IDF/AF. That can't be confirmed, though Tim McElhaw of 208 (later OC 14 in the Canberra era) certainly got two Egyptian Spit Vs on 22 May 1948, and on 7 January 1949 B.Spragg of No 6 squadron, flying an RAF Tempest, shot down an IDF/AF Spitfire IX.
There are also persistent reports that a Venom mate got a kill during the Suez op (perhaps on 5 November, perhaps Flg. Off. Dave Williams of No.249, his victim being a Meteor), and that a Hunter bloke got a manoeuvre kill against a MiG-17 during the Confrontation (there are lots of references to this: eg: "a Hunter got into a maneuvering contest with a MiG-17, which resulted in the MiG pilot flying his aircraft into the ground. If this actually happened, it was the only air-to-air kill of the Hunter in British service"), and that a Javelin crew got a C-130 (eg: "but the Javelin held on for a few years longer in the Far East, where it gained its only air to air victory - an Indonesian C-130 which crashed while trying to avoid a Javelin that had been sent to intercept it during the Malayan crisis in 1964.")
The Phantom/Jag kill wasn't the first RAF own goal, either, a Lightning F2A (flown by M Valasek?) having earlier downed a Harrier GR3......
Nor was MiG-Eater's kill the only such victory in the Gulf War. On 17 January 1991 a JP233 bomblet dropped by an RAF Tornado GR.Mk.1 did for an Iraqi MiG-25PD as it attempted to take off.