I'd love to see a little man/lady in HMRC trying to chase APD payment after seven days is up, from a multitude of visiting, non-domiciled business jets on say 'offshore' registers, the Russians, Nigerians etc.
They don't need too, they just chase the FBO.
Bit of a poor show really, effectively an honesty tax and for non UK operators they don't need to be all that honest as the UK ground handlers will pick up the tab!
Quite a minefield for UK Ficsal Rep's (& Admin Rep's)too, if the OPR cocks up or 'lacks honesty' the Rep get's hit financially instead.
No surprise handlers are not forthcoming to act for OPR's.
As a Fiscal Rep I'd be charging a pretty penny on top of the duty too!