As theoretically they are registered in the UK, even though we all know they are probably physically in St Vincent or Israel, they do need to comply with UK law. Because the personnel are operating outside the UK it would make it difficult for them to defend any action brought against them in UK courts. I would have filed a claim in the UK County Court and they would have been forced to defend it in court or not contest the claim. However even if found guilty in the court, enforcement of any judgement would be difficult as all their assets are outside of UK jurisdiction. Only a notional office address with no physical assets to seize.
At that point the company would be shut down in the UK, but they just carry on in whatever country they are located. Makes a mockery of it all really.