Boris Johnson has called in the big guns to help plan his proposed 'hub' airport in the south-east. He has employed award winning architect Zaha Hadid, who designed the Aquatics Centre used during London 2012. Simon Harris has more.
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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.