Twitter has launched a "report tweet" feature aimed at helping people who receive abusive messages.
A number of womern were recently targeted on the site, including Walthamstow MP Stella Creasy. Over one hundred thousand people signed a petition to get the site to improve its procedures for dealing with abuse.
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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.