A few weeks ago I received a copy of AOC from a friend of mine of Direct Fly in Poland and now the UK reg airplanes type Citation II and King Air are listed on their AOC. My friend who is flying for them told me that the lease is long term, around 5-10 years and that Direct Fly is currently leasing more G-Reg Citation II airplanes.
I guess Direct Fly is pioneering in operating G-Reg airplanes out of their Poland base, having all EU rights to operate freely within the EU and beyond.