When I raised the question of LN-OEA operating from Norwich, they told me... "
The reason the AW 139 is on Norwegian registry is because it is operated by Norsk Helikopterservice AS (NHS) and subsequently leased to Bond Offshore."
The Norwegian register lists it as below - where the owner (in normal type) differs from the Operator, the Norwegian CAA (known as Luftfartstilsynet locally) put the operator it italics underneath.
International Aviation Leasing have
6xAS332 and 2xEC225 on the G register, all in the G-RED# series.