A British teen found guilty of attacking PayPal and other large companies as part of an Anonymous group cyber-campaign would have been sent to jail were it not for his age and troubled personality, a judge has said.

Jake Birchall, 16 years old at the time of the offences and now 18, previously admitted to having taken part in a series of high-profile DDoS attacks on a range of companies between 1 August 2010 and 22 January 2011, the time of his arrest.

The judge at Southwark Crown Court in London, Peter Testar, sentenced Birchall to an 18-month youth rehabilitation order and 60-hours of unpaid community work, describing the youth on the basis of psychiatric pre-sentencing reports as "profoundly isolated."

"I have to sentence you with the fact that you were under 18 when convicted in mind," explained Judge Testar.

"There's a statement of special needs in your case. You have met the diagnosed criteria for certain conditions," he added without elaborating further.

The attacks were successful enough to have disrupted PayPal to the tune of £3.5 million, it was earlier alleged.

"You played a prominent role in this serious case. Nobody knows quite how much damage was caused, which potentially could have caused a lot more damage," said Judge Testar.

Last week, two of Birchall's informal accomplices in the same 'Anonymous' group attacks, Christopher Weatherhead, 22, and Ashley Rhodes, 28, were sentenced to 18 months in prison, and a suspended 18th month sentence, respectively.