Metropolitan Police Commissioner Bernard Hogan-Howe believes that stop and search has improved. He says he get "less complaints" than he did. He added that the overall amount of stop and search has been reduced by 40 per cent.
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The man was taken early this morning to a south London police station where he remains in custody.
Officers arrested a 15-year-old boy in Stratford on Saturday night on suspicion of grievous bodily harm.
Six people were injured after they were hit with the substance during an "altercation" between two groups at a shopping in east London.