The metal container information is interesting.
I went through LCY for the first time 10 days ago and took a can of coke in may bag, just to see (I didn't want to risk a bottle of something I would actually drink!). My bag was pulled - and I was told it was because of the can of coke! I mentioned that I had been told it was ok to keep it in my bag, and the nice security person said I was quite correct but they now needed to take it out of my bag and send the can of coke through again on it's own. I smiled and waited while they sent my can of coke through again on it's own.

There didn't seem to be any point in trying to say that, if they wanted to scan it separately, why did they tell me to keep all my liquids in my bag?