A teenager jointly accused of killing a schoolboy said he was “cruising for girls” on the morning of the fatal attack, a court has heard.

The 17-year-old from Brixton, who cannot be identified for legal reasons, told the Old Bailey he was “just a passenger” in a stolen Nissan car which was filmed speeding away from Gipsy Hill Gardens, where 15-year-old Zac Olumegbon from Brixton Hill was stabbed to death.

Giving evidence today, the defendant, who with four other boy’s deny murder, said the group, known as the GAS gang, was touring schools in south London to meet girls, but said he could not remember which schools they planned to visit.

Edward Brown QC, prosecuting, said the defendant was instead part of a “team” who planned the attack outside the Park Campus School in West Norwood on July 2.

The defendant said after the group returned to the car after the attack, another defendant said to him “I think I stabbed someone”.

In response, Mr Brown said: “The cruising for girls had gone badly wrong. Surely there would have been surprise, questions, things like that?”

The defendant said: “There might have been talk between the driver [of the car] and the front passenger, but not with me. I took what he said as a joke. He is not that type of person.”

Mr Brown said the gang’s name stood for ‘Guns and Shanks’ or ‘Guns and Knives’ but the defendant said it meant ‘Grinding and Stacking’, or ‘Working hard and saving money’.

Jurors were shown footage from a video posted on YouTube, which featured members of the GAS gang rapping about hiding knives in their trainers.

Mr Brown accused the defendant of lying “to avoid responsibility for Zac’s murder” when he claimed another defendant had taken the murdered boy’s mobile phone in his original statement to the police.

It later emerged he had taken the phone himself.

Mr Brown said: “There were 52 seconds between you running up [Gipsy Hill Road] and you being in the car leaving. What were you doing for all that time?”

The defendant replied: “For all that time? That is not a lot of time sir. I picked up [Zac’s] telephone and ran to the car.”

Mr Brown said: “You were down that passageway after Zac weren’t you?”

The defendant said: “It is not true”.

The defendant added he was “shocked” to be told about a text message which read “RIP Zac”, saying “I did not witness anyone getting stabbed”.

The court heard the five defendants met at a house in Stockwell the night before the incident on July 2, 2010, and stayed the there until early the next day, when they travelled south towards Park Campus School in the stolen car.

As they drove past the school, they saw Zac standing outside, and four members of the gang exited the car to chase him.

The schoolboy, who was part of or associated with a rival Tulse Hill gang called TN1, was later found by school staff with stab wounds to his heart, neck and buttock.

Five youths, four aged 17 and a boy of 16, from Brixton, Stockwell and Clapham, deny murder.

The four 17-year-olds also deny wounding with intent on the 14 year-old-boy. The 16-year-old has admitted the charge.

The trial continues.