A MOTHER who accused her chief executive husband of having an affair spent weeks researching drowning methods before holding her three year old daughter's head under water in the bath to kill her, a court heard yesterday.

Former science teacher Claire Colebourn allegedly even watched an American YouTube video called 'someone dies in the tub everyday'.

Jurors were also told that after the birth of daughter Bethan, the 36-year-old would regularly shout and swear so loudly at her luxury marine interior firm exec husband Michael, 38, that neighbours could hear.

A month after he left her and moved out of the family home, Colebourn killed their daughter, the court heard.

Police rushed to the £400,000 Fordingbridge bungalow on October 19, 2017 after Claire's mother, Janet Fildew, went to the house and discovered her granddaughter's body.

As paramedics attempted to save Bethan, who is believed to have laid dead for almost a day, she still had soaking wet hair and fluid was coming from her mouth.

Type-one diabetic Colebourn also had to be treated, having allegedly given herself a huge dose of insulin – around ten times the normal 30 unit daily amount.

It has been heard Colebourn mistakenly believed her husband Michael had been having an affair with a colleague at his company, Trimline.

Jurors were told she drowned little Bethan because she did not want her to have anything to do with Mr Colebourn, claiming she was saving her from him.

Prosecutor Kerry Maylin told Winchester Crown Court Colebourn researched 'how to kill by drowning' and if drowning was 'relatively painless'.

Ms Maylin said: "We can also see entries for dating sites. There's a search for country-wide dating and a site called Muddy Matches.

"There is also searches for how to find a farmer to date, single farmers New Forest and 'why is husband so adamant to leave'."

It was heard Colebourn would often get into blazing rows with her husband, shouting and swearing at him.

Neighbour Richard Smee, whose house backs on to the Colebourns', said the accused sounded like the "dominant" one in the arguments, not her husband.

Mr Smee's wife Lynette added: "I remember hearing quite a lot of arguments between the couple.

"The lady would use swear words. It became so loud, we no longer had to try to listen, we could just hear it."

After being arrested, the court heard Colebourn told police: "Bethan said 'I don't want a bath mummy, I don't want a bath'.

"I drowned my own daughter. I think, sadly, she had complete trust in me."

Colebourn denies murdering her daughter. The trial continues next week.