Jordan Monaghan, 30, obstructed the airways of Ruby, aged 24 days, and Logan, 21 months, in January and August 2013.

Six years later, the gambling addict killed his new girlfriend, Evie Adams, 23, with a drug overdose in October 2019.

He has been given three mandatory life sentences and ordered to serve a minimum of 40 years after he was found guilty at Preston Crown Court.

Laura Gray, the children's mother, was heard weeping in the public gallery as the verdicts were given following a 10-week trial at Preston Crown Court.

Ruby was smothered as she slept in her Moses basket on New Year's Day in 2013.

Eight months later, after Ms Gray discovered Monaghan owed thousands of pounds in gambling debts, she told him the relationship was over.

The next day he took their son, Logan, to a local swimming pool, Waves in Blackburn.

He smothered the boy in a cubicle in the changing rooms, the jury heard.

Ruby's death was initially attributed to bronchiolitis, while Logan's was described as "unascertained".

Doctors had seen both children in the days and months before their deaths, but only usual childhood illnesses were found.

Monaghan, a construction worker, was arrested in 2018 after new information came to light about the deaths of the children.

Ms Adams, a mother-of-one who suffered "chronic abuse" before becoming a foster child aged 12, was warned by police not to be with Monaghan.

But the relationship continued until she threatened to dump Monaghan, who told her: "I won't keep putting up with you saying we are over."

When he murdered Ms Adams with a cocktail of prescription drugs, he was on police bail for the youngsters' murder.

Ms Adams was found to have tramadol, diazepam, amitriptyline, zopiclone and pregabalin in her body, and died from tramadol and diazepam toxicity.

Monaghan then faked a suicide note from her.

He was re-arrested in January this year and charged with all three murders. He killed because he could not face rejection, the court heard during his 10-week trial.

He claimed to have had nothing to do with the death of his children, but a dozen experts told the court that while the exact cause of the deaths was difficult to pin down, imposed airway obstruction was either "likely" or could not be ruled out.

Monaghan also claimed the illegal prescription drugs were for himself and denied ever giving any to Ms Adams.

He was convicted of the three murders and two counts of attempted murder to a third child who cannot be identified for legal reasons.

He was not in court to hear the verdicts after suffering from a minor illness.