According to "Manx Aviation in War and Peace" by Gordon Kniveton 1985, an excellent reference work:
G-AGUP was operated just after the end of WWII by Isle of Man Air Services to join two others providing services to/from Liverpool and Belfast from Ronaldsway then (until January 1946) HMS Urley, Routes were extended to include Blackpool and Manchester. Services ceased on 1 February 1947 when the nationalisation of all airlines to create BEA occurred. BEA took over all IoM scheduled services in the summer of 1947. I have no idea what happened in the brief period between stop and start although it seems BEA took on the Rapides.
There's a lot more in the book but it is no longer in print.