Dave,
I work a lot with Construction Contracts and the presiding rule of thumb is that it generally follows that the law in the country in which the contract is formed takes precedent. So, if the contract was signed in England under English law, then the warranty would follow suit (should there be a claim under the contract and/or warranty), irrespective of where the work was physically undertaken - apologies if I've misunderstood what you've said above, and I don't aim to unpick what you've stated, I'm actually interested from the contract perspective.
I suppose to short-circuit my text above, if an overseas buyer contracted with a UK shop, does the associated warranty not support this purchase?
Finally, I've got 'Enterprise', 'Reliance' and await 'Princess'. I wish I could afford more, they are fantastic models.