[MatthewBloch]

They missed the only one I know in the UK - "Inspector Sands" I'm sure used to be associated with bomb / terror threats but wikipedia says it's just a general euphemism for something in a train/tube station that needs immediate attention from staff.

[mootothemax]

It was only after someone told me about "Inspector Sands" that I noticed how often it's used. Based on my anecdotal evidence, it totally makes sense to use all these codewords, otherwise half the stations in London would be closed on a daily basis :)