Boris Johnson is expected to visit the Crossrail site at Tottenham court road later.
The mayor will be questioned on yesterday's government spending review.
A commitment of £2 million was made to look into the north-south rail link for cross rail 2 in yesterday's spending report by George Osborne.
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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.