>Being an ex-RAF machine rather than a civilian SA341G or J, wouldn't it have been operated under a Permit To Fly as opposed to a CofA?<
From G-INFO:
EASA Category: NON EASA
Engines: 1 x TURBOMECA ASTAZOU IIIN2
MTOW: 1900kg
Total Hours: 9525 at 31/12/2013
Year Built: 1973
Approved Maint. Programme: None
CofA/Permit: Permit to Fly
Permit Validity Expiry: 04/08/2015