G registered A350’s
Some people forget just how good T’s & C’s are now, compared to those of not so many years ago. Be careful how much you rock the boat, you wont realise you've rocked too far until its unrecoverable and the boat rolls over!
Its entirely plausible for the company to have London based pilots, on UK contracts (think F/A crew base). No reason why the airframes can’t be adorned with a UK, G prefix registration, either!