Alison Munro, the chief executive of High Speed Two Ltd said: "This is a project that the country needs. The existing railway is becoming increasingly full and by the middle of the next decade parts of it will be effectively full.
"So we need to start now to plan to have that capacity in place."
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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.