First all, thanks a lot for all your help. We're back in the UK and had a truly wonderful stay in Japan. We did pretty much everything we wanted to, and managed to optimise our itinerary (17 nights in total) using the invaluable advice from this forum.
On to train pushers...
My original plan was to go to Ueno station this past Monday morning at rush hour and observe from a safe distance. But one should be careful for what one wishes for as I ended up having a more, er, interactive experience.
I was travelling from Shibuya to Shinjuku on Friday night about 11.30pm. The Yamanote line platform queue at Shibuya was about 10-person deep, and I thought that there was no way I was going to get onto the train. However, once the train arrived, the crowd just became a solid mass and I was pushed into the train. So far so good.
There was a person a few rows behind me who wasn't quite so lucky. As he was getting into the train he actually managed to fall in between the platform and the train itself. It's hard to describe the scene, but there were people everywhere so it was hard to see what was going on, but a few passengers were trying to pull him up.
Now if this were to occur on the London Underground, it would probably be enough to severely delay the train, close the platform to avoid overcrowding, etc. However, the station attendant saw what had happened, walked calmly over, yanked this guy up back onto the platform and then pushed him into the carriage before the doors shut.