Anti-capitalism protesters from the Occupy movement have begun a new protest in the City of London as part of a global day of action.
Other protests are underway in cities including Moscow, New York, Athens and Madrid.
Several hundred people have gathered outside St Paul's Cathedral for a rally, before moving on to demonstrate outside the offices of some of the largest firms in the financial heart of London.
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Specialist explosive detection dogs searched through the town examining letter boxes and phone booths for signs of potential devices.
Temperatures soared to 27.9C in Northolt shortly after midday on Thursday, making it the warmest April day for 69 years.
The South East will enjoy the best of the weather and along with Paris will be the hottest place in Europe.