He said he could not reach any conclusion but, in her state at that time, she intended to kill the boys, pointing out that she had “unspeakably” held the boys under water for “up to a minute or two”.

“The bath was probably still run from their normal evening routine and I do not think for a moment that your dreadful acts were pre-meditated,” he said.

The judge said Alexander dried the boys, put them in clean pyjamas and laid them together, tucked in under duvets, on the same bunk bed.

“The next morning, their father, worried by your unusual silence, came and found them. The stuff of nightmares,” he said.

The judge said there was every sign Alexander was a “caring and affectionate” mother to both children before the events of Dec 15.

He pointed out that their father said Alexander “never shouted or raised her voice at the boys” and “never showed violence to the boys”.

Psychotic state caused by cannabis 

Mr Justice Bennathan said Alexander was in a psychotic state when she killed her sons and that it was cannabis induced.

He said she had a previous psychotic episode in 2016 in which cannabis also probably played a part, but said he cannot be sure that she was aware that cannabis could trigger another psychotic state.

The judge said he noted that in Dec 2022, Alexander spoke regularly with two members of her social circle about her heavy cannabis use, both of them knowing that she was looking after two small children.

“And at least one of them knew of your previous psychotic episode in 2016, yet neither of them warned you of any risk or sounded any note of caution at all,” he said.

The judge said Alexander will mourn her sons for the rest of her life.

“From all that I have read and seen of you, I have no doubt that every day when you awake you will remember and grieve for the little boys whose lives you snatched away,” he said.