A father accused of killing his 12-year-old son by shaking him as a five-week-old baby at their home in Kilburn insisted he could not have caused the fatal injuries.

Allan Young, 36, allegedly shook his baby son Michael so hard he was left with brain damage, severe cerebral palsy, blind, and with a twisted spine that eventually killed him.

But the Scottish-born father told the Old Bailey he could not be responsible for the injuries because he did not shake Michael that hard at his then home in Belsize Road.

He said: “I know how I shook him, and I didn’t shake him that much, not with the excessive force that’s been explained.”

Michael had the mental age of a six-week old baby when he died aged 12, and was incontinent and had to be fed through a tube.

His spine was so deformed that, as he grew older, it crushed his organs until he stopped breathing on January 23, 2011.

In a landmark case, Young, who had already served a year in prison for attacking his son, was charged with manslaughter and is now back on trial.

Young admitted shaking Michael in the early hours of April 16, 1998, when the baby would not stop crying.

He said he pleaded guilty to the attack on the advice of his solicitors, but could not remember seeing any medical evidence at the time.

He said he confessed only after doctors had asked if Michael had suffered a fall or had been shaken.

After he was released from jail he rebuilt his life with a new partner, Michelle, and they have a young daughter together in Scotland.

But he said he remains on anti-depressants and quit his job when arrested against in 2011.

Young from Lanarkshire, denies manslaughter.

The trial continues.

Related link: Father on trial over death of son after shaking him as a baby in their Kilburn home