The family of landscape architect John Hopkins have planted an oak tree in the Olympic Park to remember him. Mr Hopkins helped to design the park before the 2012 Games but died in January.
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Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.
The family of Oliver Dearlove urged people to "think again" before using their fists, as the man who killed him began a six-year jail term.
London Fire Brigade took Southwark Council to court on four charges in relation to safety breaches at Lakanal House in Camberwell.