Seems we've all been head-scratching over the same clues this week. I had similar trouble parsing 3A until eventually coming to the same conclusion as Darla. Still don't like the 'one through' device, though. Meanwhile, 25A was also driving me crazy, as I was looking for a way for the first THREE letters to mean Lawrence, rather than the next 2. Doh!
Couple of definition quibbles: I agree with Jono re 10A (which I guess is what was meant), but also the 'laws' homophone in 13D is a bit of a stretch. Otherwise, good fun. As, hopefully, this evening will be. Come on Wales!