Half way across a road, and suddenly the traffic on one side of the road heading up towards Euston station thinned out.
Only to be replaced by mad whistling. And for a full minute, hundreds of people on roller skates zoomed past. No idea who they were. Or what they were doing. But they were well-marshalled, and enjoyed a police motorbike escort!
Seeking enlightenment, I quickly checked flickr – but no (similarly blurry!) photos turned up with appropriate dates and tags. So if you’re reading AiB and you have any ideas what was going on, drop me a comment.