In November 2012, the unmistakeable tones of Barbara Windsor could be heard over the tannoy, as she encouraged Tube passengers to give to the London Poppy Appeal.
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Paramedics were on standby outside the police cordon as armed officers stood by the property.
A team of researchers has taken samples from the ten busiest London Underground lines to work out which are the dirtiest.
The action comes on top of an emergency timetable which has seen hundreds of trains a day being axed.