Police Officers say they fear a repeat of last summer's riots, according to a new study.
The research, carried out by the London School of Economics and the Guardian, also suggests that police don't have the resources to cope with such disorder.
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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.