Thanks everyone. If just one person reads it and realises something they didn't realise before, it worked. Oh, I've corrected a potentially misteading typo - I'd typed 'as if turning light', instead of 'left'. See, I can't get left and right sorted out!
Good points about having escape routes in case of poor driving, , about being invisible right under the windscreen and about it applying to buses too - any long vehicle basically. It was a bus that taught me the lesson about going up the left of left turning vehicles, about a dozen years ago. There were pedestrian railings, and I was lucky to only get my handlebars twisted.
I have a huge respect for anyone who can drive such a huge vehicle in congested towns. I get stressed enough in a car. And I know that the vast majority of such drivers are excellent. But a human being can only take in so much information, so extra cameras and mirrors and alerts only work up to a degree. Let's help the good guys by keeping out of their way, and help ourselves by giving the less good guys a wide berth...