The co-defendant in the the Tulisa Contostavlos trial has also walked free after the judge decided the case against him could not proceed.
Rapper Michael Coombs, whose stage name is Mike GLC, had pleaded guilty before the trial to supplying half a gram of cocaine to undercover reporter Mazher Mahmood.
On hearing the decision the 36-year-old reportedly wept and hugged his defence barrister, Jeremy Dein QC.
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Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.
Windy this weekend with gales across northwestern parts of the UK. Rain spreading southeast.
Greater Manchester Police said "inquiries are ongoing to fully understand the circumstances of the incident."