Thanks for the comments all, really looking forward to the next one.
Soeren, love how you flipped between the two modes of sketching on the crawl - your atmospheric marker sketches (which my brain still can't comprehend how they're put together!) and those gorgeously detailed statue studies.
Brin, like Tom says, great use of light and shade. I wish I could see tones like you do, but when I look at a scene, all I see is line! Really fantastic mix of subjects too with the displays, people, and I love the detail of the blue biro drawing of the building in sloane square.
Oh, and thanks for all the links guys. First thing I did when I got home that Saturday was google Rad-how-to's blog, and Biocreep (who Chris mentioned). It all blew my mind. Tom, those last two links you've posted are real treasure troves of information! It'll be a while before I need to buy another book! JP's blog too is utterly fantastic.
The guy I was talking about was David Pimentel, his blog is here:http://drawingsfromamexican.blogspot.com/
love his gestures.