Singers Annie Lennox and Radiohead frontman Thom Yorke, as well as actor Ewan McGregor, have all shown their support to six activists who have been climbing the Shard in protest of oil drilling in the Arctic.
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George Michael died in December last year at the age of 53.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.