Cyclists will stage another mass protest later tonight demanding Boris Johnson to redesign London's streets, saying they need to be made safer for cycling.
Three cyclists have died on the capital's roads in the past three weeks.
Luke Handrahan reports.
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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.