A “culture of racist bullying and harassment” that infected a secondary school led to a bloody hammer attack which wrecked a pupil’s life, a top judge has been told.

“Undue indulgence and leniency” towards disaffected Asian pupils at the 1,400-pupil Ridgeway Foundation School, in Wroughton, created an “obvious risk of racial violence” for which 15-year-old Henry Webster paid a terrible price, said his barrister, Robert Glancy QC.

Members of a schoolyard gang known as ‘Asian Invasion’ – along with young men from outside the school thought to have been summoned by mobile phone – savagely beat bullying victim Henry near the school’s tennis courts in January 2007, London’s High Court heard.

One of the outsiders laid into him with a claw hammer, fracturing his skull and causing devastating brain damage. Now the teenager, of Wroughton, is mounting a unique bid for massive compensation from the school.

Thirteen young men and boys were sentenced for their parts in the incident following two trials at Bristol Crown Court last year.

Setting out his case, Mr Glancy told Mr Justice Holroyde: “We say there was a failure to provide security at the school and to prevent intrusion by trespassers. There was also a failure to supervise the tennis courts exit from the school and a failure to impose and maintain adequate disciplinary standards, including control of the group of pupils known as ‘Asian Invasion’.

“There was a failure to deal with racial tensions and incidents, or to promote good relations between different racial groups. The pattern of events over several years led to the inhuman and degrading treatment of Henry and a breach of his human rights.

“They should at least have put up a security fence, as they did almost immediately after the attack on Henry. We say that the net effect of all this led to the incident in January 2007.”

However, Ronald Walker QC, for the school, pointed out that the attack on Henry took place after school hours and insisted that, short of stopping and searching every visitor, nothing could have been done to prevent what happened.

The school’s duty was to discipline pupils, not outside adults, and arguments that laxity in enforcing school rules contributed to the attack on Henry were described by Mr Walker as “fanciful” and “implausible”.

Denying the school has any liability to compensate Henry, the QC added: “The idea that some sort of disciplinary system would have been effective in preventing an Asian pupil contacting his brother on his mobile phone is, again, fanciful”.

Henry’s compensation bid will now go ahead for a full High Court hearing which is expected to start on October 19 and which is due to last five weeks.

If Henry, now 18, wins his case, he could be in line for seven-figure compensation. His younger brother, Joseph, his mother Elizabeth, and his stepfather, Roger Durnford, who all say they were left deeply traumatised by witnessing Henry fighting for his life, are also seeking damages payouts.