Joanna Dennehy, 30, has pleaded guilty at the Old Bailey to the murders of three men who were found in remote ditches in Cambridgeshire with stab wounds.
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The band announced at a free concert on Friday that they would take over the event's Pyramid stage on Saturday June 25.
The victims were collecting permits and escorts a day after their home town was liberated from the extremists.
Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.