Service number seems to be the way forward, even worked for me (VRT).
Of course we are all (quite rightly) listed as Fg Offs regardless of acting rank. When did honours start to be listed as acting ranks? Until recently any VRT getting an honour (e.g. for 30+ years in service) was listed as Fg Off, but recently I've seen Wg Cdrs and Sqn Ldrs. As there are no substantive ranks above Fg Off in the VRT this seems a bit waltish.
Tim