Stronger, surely. We know what a principled person is, but a principled thing has an ambiguous feel to it. We couldn't be sure whether an objection was being made on principle or in principle. People who do things on principle can be tiresome, tending to have closed minds, and to forget that circumstances alter cases. Those who object to something in principle are saying that they are willing to be reasonable and that they wouldn't jib at a few riders, the sort that start "Except in so far as". It would have been nice to know at the time which class Mr Redwood was putting himself into.
No one can be sure yet what William Hague's principles are, but the less he talks about them the better. The word comes from the same root as prince and was originally to do with pre-eminence, so a principle was a pre-eminent, overriding truth, but it has since become a relative term - one man's principle can be another man's poison. Bernard Shaw complained that "the Englishman does everything on principle" whatever the cause being plugged. Mr Hague should remember Disraeli's advice to Bulwer Lytton: "Damn your principles. Stick to your party."