The father of a boy who was killed by his mother has told a court how the killer apologised, saying: "I’m so sorry, I didn’t know what I was doing."

George Acres died after being strangled and drowned by his mum, Christina Acres.

In a statement read to the court George's father, Gary Acres, said: "When I arrived at the house I saw Christina’s mother standing over the bath tub.

"She told me Christina was downstairs. I walked into the living room, where she said ‘I’m sorry, I’m so sorry, I didn’t know what I was doing’.”

Judge Christina Lambert told the jury two expert psychiatrists believe she is not guilty of murder by reason of insanity, and that the prosecution and defence also believe the same.

Addressing the jury, she said: “It’s unusual and is very, very sad.

“The defendant Christina Acres is charged with the murder of her son George Acres in July last year.

“She does not dispute that she killed him.

"But the question you are going to have to decide is whether or not she is not guilty of murder by reason of insanity.

“The prosecution and defence are in agreement that Christina Acres is not guilty by reason of insanity.”

She told the jury if they do not agree they must determine if she is guilty of manslaughter by diminished responsibility.

George Acres was found unconscious at his home in Rochford Garden Way on July 23 last year, and died later in hospital.

The trial continues.