Funny you should ask this. I accidentally left mine (1 litre aluminium) in my handbaggage two weeks ago when travelling from EDI. I took it out and asked the security chap if it was OK, explaining that I'd forgotten it but it was empty. He said as long as it's empty it's fine. He didn't check, just put it through and all was well.
I was very surprised as I thought that no containers were allowed, empty or full, and I expected to be barked at and told to throw it in the bin.