Metropolitan Police Commissioner Sir Bernard Hogan-Howe said that he was "shocked" by allegations that undercover officers hunted for information to smear the family of murdered teenager Stephen Lawrence.
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The robbers casually approached their victim on a busy high street before before spraying a noxious substance in his face.
Tencho Hristov ignored warnings and got trapped between barriers at Roydon in Essex.
The 6km bike track will include 130m of the South Circular near Kew Bridge.