Yesterday, the only Tube station that has nothing in common with a mackerel had a deadly gas attack simulation to see how quickly toxic substances would spread in a real terrorist situation. Scientists released harmless sulphur hexafluoiride (a gas used in tennis balls) into parts of the station and then meausured air flow and penetration levels. The station was open as normal during the exercise and apparently will be repeated this coming Sunday.
Just in case you were wondering "The St John's Wood trials were announced earlier this month by Transport Secretary Douglas Alexander who made clear the tests were not a reaction to any threat increase or a measure to enhance security at Tube stations." according to the report on 24 dash
A Department for Transport official said: "We want to be able to find out how quickly the substance moves around and where it goes to.
"St John's Wood was chosen as a typical Tube station with just one way in and out and with one up and one down escalator."
Were you around the station at all on Sunday and did you notice anything?
I wonder if the experiment will be repeated on the trains themselves though. I caught a really sulphuric whiff of something on my Piccadilly Line carriage this morning. But in true Tube form, no one else showed any signs of noticing the rotten egg smell - which fortunately disappeared after a minute or so.