Can't reply specifically about BA/VS but the duty time may factor into the equation at some point...maybe.
Example, from rather long ago.
Several pilots at TWA, being senior and dual nationals (UK/USA) decided they would rather live in the UK, and fly out of JFK (base) to LHR.
So far so good.
They would usually deadhead to JFK the day before, have crew rest, then operate.
This became rather a drag, so then the scenario was changed to deadhead to JFK, then operate three hours later, JFK-LHR.
This went on for awhile until....
A TWA 747 was noticed descending from the overcast at 400agl, with the landing gear still neatly folded in the wheel wells.
Opps!
The tower noticed of course, and the aircraft went around.
TWA management got wind of this straight away of course, and the Captain ahhh, retired, the F/E likewise, and the First Officer received a year off without pay.
Oh yes, the idea of avoiding US taxes didn't work either, as the IRS disallowed the idea, and the UK Inland Revenue wanted their slice as well.
An expensive scenario for all concerned.
Another group from TWA decided they would rather live in the Bahamas, and commute to JFK.
No US residency, no US taxes?
That didn't work either, as the IRS decided otherwise.
Some of the TWA guys were quite clever, to no avail...
