A mother has described in court the moment she came downstairs to find her four-week-old baby floppy and grey after her partner allegedly shook him so violently he caused brain damage.

Atticus Bartlett collapsed at the family home in Chard, Somerset, after the alleged attack by his father, Tony Bartlett, 39, who was a postal worker. He denies murder and manslaughter.

Bristol crown court was told Bartlett had been left alone to feed the baby at the end of a night out during which he drank up to nine pints of beer.

The baby’s mother, Evelyn Ballentyne, told the jury that when she came downstairs on the night of 16 July 2022 her child was making “gasping noises”.

She said: “If you have ever watched someone pass away, towards the end of their life, they make funny noises and that’s what he did.

“I then stared at Atticus for a couple of seconds and you could just tell that he had gone grey. He was dead. I don’t know if I said: ‘He’s dead’ or: ‘He’s not breathing.’ I screamed.”

Ballentyne said Atticus had been lying face down on his father’s knees and Bartlett “flipped” him over. “Atticus’s head just flopped back, he wasn’t alive,” she told the court.

Prosecuting, Charles Row KC asked Ballentyne how many times she had thought about what happened that night. She wept and replied: “All the time.”

The court heard Ballentyne previously gave accounts that she had picked Atticus up and gently shaken him to revive him. However, she told the jury this was not what happened. “My memory is very clear now of that night,” she said.

Representing Bartlett, Nigel Power KC suggested Ballentyne had sought to “minimise” her actions, which she denied. He asked her: “Tony didn’t do anything to harm Atticus, did he?” Ballentyne replied: “Yes he did.”

Atticus had been cared for by his grandmother, Rachel Donovan, and her husband, Andrew, earlier in the evening, while Bartlett and Ballentyne went to a pub and comedy club.

Row told the jury that Bartlett had drunk up to nine pints of beer and was left to feed Atticus while his partner went upstairs to change at about 11pm.

He alleged that while Ballentyne was upstairs, Bartlett violently shook Atticus so hard he caused severe injuries to his brain and spinal cord. Several of Atticus’s ribs were also cracked.

Atticus was taken to Musgrove Park hospital in Taunton by ambulance staff and transferred to Bristol Royal hospital for children.

However, his brain damage was so severe that Atticus never breathed for himself again and did not regain consciousness. He died just before midnight on 23 July 2022.

The trial continues.