People sometimes get psycho if they think they're going to be late in the mornings.
Some bloke at Holborn tube launched into this tirade of verbal abuse about some woman whose bag was in his way once, and started calling her fat and stupid etc. Really nasty.
Also, during one of the tube strikes I was on a bus in Finsbury Park and this guy was totally losing it, barging past people saying "I've got to get to work! I've got to get to work!" over and over.
I mean, fair enough if you are an ER doctor or a fireman, but I doubt either of those two was. Fortunately most places I've worked in London have been ok with a bit of lateness, because that's the nature of our fair city...