Asif Kapadia, the director of documentary 'Senna' about the Brazilian motor racing champion Ayrton Senna, was one of the artists that contributed to the Secret Postcard Sale.
Here the former Royal College of Art student talks to ITV London about the experience:
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Officers believe the three assaults are linked and are appealing for information about the suspect.
Nine addresses in Lewisham were searched and 13 arrests made early on Tuesday morning in a planned, intelligence-led operation.
The Purple Rain singer died in April 2016