Random thoughts...
I moved from London 3 years ago now. The first time I went back, 2 years ago, the increase in number of bikes on the road was incredible. The 2nd time I was back, cycling had become as much fashion statement as anything else. Ok, that element has always had been there to an extent but it was in your face now; seemed like every other cyclist was on a wacky coloured Charge fixie, stubby little handlebars and wearing 3/4 knicks. Last year, there was even a cyclists' café open (in Hoxton I think). Cycling was very much part of London culture. (Why, I've even seen a feature on it on the French news recently!)
On all visits, it seemed a disregard for traffic lights was pretty much the norm. I'd often see cyclists forming scrums in ASLs, some track standing. It was in part inspiring to see cyclists almost taking over the road, and partly unnerving as I could see potential for dispute.
I look forward to my next visit (projected to be May 2011) and I'm interested to see how things on the road are then. I want to have a go on a 'Boris bike' too.
The Chiltern line; I loved it and Marylebone was my favourite London station - like stepping back into an Ealing film. I used to live around there (and Ealing too for that matter, once upon a time) and the Chiltern line was a weekend escape route out of London. Many of my rides started with a train journey from there so I have fond memories. I liked the coffee from the little stall there, can't remember it's name but a chain/franchise of some kind. And the fact the staff on the ticket barriers always had a few pleasant words for me as they let me through with the bike. There seemed nothing manic about the place... but I guess it was Sunday morning!