The woman who murdered 16-month-old Star Hobson after inflicting “utterly catastrophic” injuries has been jailed for life, with a minimum term of 25 years.

Star suffered weeks of “neglect, cruelty and injury” by Savannah Brockhill, 28, at a flat in Keighley, West Yorkshire. The toddler died of cardiac arrest after being punched or kicked by Brockhill in September 2020. A post-mortem revealed previous brain injuries, fractured bones, including Star’s ribs, tibia and skull and injury to internal organs.

Brockhill’s partner, Frankie Smith, Star’s mother, was jailed for eight years after she was found guilty of causing or allowing the toddler’s death. The maximum sentence for the offence is 14 years imprisonment. The 20-year-old was cleared of murder and manslaughter charges after the jury accepted she had not encouraged the fatal attack.

Brockhill and Smith had been in a “toxic” relationship for 10 months at the time of the murder. Smith’s barrister, addressing the court on Wednesday, said that Star’s mother had been “plainly unaware of the seriousness of the assaults. “She is herself a victim of the murder count, having lost her daughter”, said Zafar Ali QC.

Brockhill’s lawyer said her client collapsed at the beginning of the trial and suffered three seizures and two cardiac arrests. Kath Goddard QC said she discharged herself from hospital so the trial could continue but the cause of this illness has not yet been determined.

Brockhill, an amateur boxer and security guard, denied all charges against her. Halfway through the seven-week trial, Smith pleaded guilty to eight instances of child cruelty against Star between April and September 2020. The court heard Smith was of extremely low intelligence, and “abnormally compliant” when told to do something by an authority figure. However, the judge said she “did not accept” that these factors excused Smith’s conduct, describing her as a “neglectful and callous parent” who thought only of her own interests.

The sentencing follows the conviction of another couple, in a separate case, of killing six-year-old Arthur Labinjo-Hughes after a “campaign of appalling cruelty” during lockdown. Arthur died in June 2020 after being deprived of food, force-fed salt and assaulted, in abuse that was filmed and photographed by his stepmother and father.

Smith and Brockhill also filmed many acts of cruelty against Star, sending them to friends, sometimes with added captions or music. The women could be heard laughing as they filmed Star falling off a chair or down the stairs. Other incidents were caught on CCTV, including one two days before Star’s death where Smith dragged her through Bradford city centre using reins. The toddler already had a broken leg as a result of one of 21 blows from Brockhill a few days earlier when she took Star to work at a recycling centre in Doncaster.

A local review of Star’s death is due to be published in January, which will feed into a national one ordered by the government following Arthur’s murder.

The first of at least five safeguarding referrals from concerned relatives and friends was made in January 2020 by Hollie Jones, Smith’s friend who the judge said was frequently “used for free babysitting”. Jones told the BBC that when social workers rang to say they were visiting, Smith spent an hour cleaning Star and covering up bruises.

Social workers visited on four occasions, and closed the case three times, while police visited once. Boris Johnson described Star’s death as “shocking and heartbreaking”, adding that lessons must be learned from the two child murders. The Department for Education said it would “not hesitate” to remove children’s services control from Bradford council if necessary.

The Bradford Partnership, which has responsibility for children’s safeguarding in the area, apologised after the convictions of the two women. A joint statement from the council, Bradford’s clinical commissioning group and West Yorkshire police, said they “deeply regret that not all the warning signs were seen”.

Bradford’s children’s services were judged inadequate in October 2018, and an Ofsted inspection in October found “significant weaknesses” remained. A government-appointed commissioner has been overseeing the department since August.