Yes, I'm David Welbourn (without the final 'e'). I have written a few small games, not in Quest, but in Inform 6. None of my games are terribly impressive, I'm afraid, but they're all in the IF Archive and listed on my IFWiki page, Baf's Guide, and my own Key & Compass pages.
As for writing new games, well, I do have some that have been eternally in progress, again in Inform 6, but I'm not a speedy author, so it may be months yet before I manage to release another game. Most of my IF efforts go towards playing and documenting other people's games, rather than writing my own.
It's unlikely I'll author anything in Quest anytime soon, but maybe someday I'll be moved to porting a game or writing something smallish in it. My brief experiences with Quest games several years ago didn't give me a good impression of the system, but this year, since the release of Quest 4, I've tried a few of the newer games, and I've actually enjoyed several of them, particularly the Sir Loin games by CJ here. And the multiplayer possibilities of Quest are... intriguing. And the textadventures.co.uk site itself is quite nice. So, even though I think Quest is a bit more primitive than I'd like, I'm also more positive about Quest than I was formerly, and I can see good things in its future.
And my apologies for the delay in replying. I only returned to the forum hoping to see discussion about Shiversword: The Beginning. Since I could, heh, use a hint.