A primary school teacher accused of stabbing her partner to death "in cold blood" before burying his body in their garden has pleaded guilty to murder.

Fiona Beal, 50, admitted killing 42-year-old Nicholas Billingham, whose partly mummified remains were discovered four and a half months after he was last seen.

Beal, who was arrested in Cumbria, had initially pleaded guilty to the lesser offence of manslaughter by reason of of a loss of control, but denied murdering Mr Billingham between October 30 and November 10 2021.

A jury at the Old Bailey heard on Friday that she had changed her plea.

Judge Mark Lucraft told Beal: "You have this morning pleaded guilty to murder, which as you have no doubt been told, carries a sentence of life imprisonment."

He confirmed he will determine the minimum term at a two-day sentencing hearing starting on May 29.

As the jury left the courtroom, a tearful Beal wiped her eyes with a tissue.

The teacher, of Moore Street, Northampton, was arrested in March 2022 after police discovered the body.

Forensic officers and specialist search teams were deployed to the address before the discovery was made.

The court heard that her actions were revealed through journal entries discovered by police.

Last week, prosecutor Hugh Davies KC told jurors that Beal, "a high-functioning professional", messaged several people on November 1 2021 - and in the days after - that she and Mr Billingham had contracted Covid-19 and needed to isolate.

The prosecutor called the narrative "sustained and dishonest" and told jurors there is "no evidence" that Beal took a Covid test.

The court heard similar messages were sent from Mr Billingham's phone from November 2.

Mr Davies told jurors the messages from Mr Billingham's phone were Beal "pretending to be him" in a move that was "as heartless as it was self-serving".

On November 8, jurors heard that Beal sent messages to her sisters saying she and Mr Billingham had split up, with one message saying he left because he had had an affair with another woman.

The prosecution said the narrative that Mr Billingham had run off with another woman was "completely false".

But jurors heard that Mr Billingham appeared to have cheated on Beal previously.

She returned to work "fully discharging her considerable responsibilities as a teacher to Year 6 pupils" and receiving a "sympathetic response" from people who had heard about her break-up.

Her mental health started to deteriorate in late February 2022, the court was told.

The following month, she rented a cabin in Cumbria and sent messages to family members which gave them cause for concern over her wellbeing, prompting them to call police to check on her, the prosecutor said.

In the cabin, police found journals "written in her hand" that showed "a wholly different side to her personality".

Mr Davies said: "They certainly do contain some unambiguously clear declarations of what she had done. These parts were not just her truth, but the truth. What was this?

"The short answer is that she had planned to, and had, killed him in cold blood. She had purchased a forged handled utility knife in the days before. She had a chisel and cable ties.

"Promising sex after a bath, she stabbed him in the neck when he was wearing a sleep mask and was probably cabled-tied on their bed."

The court previously heard that this was the second time a trial had started in the case, with a different jury - for a trial that took place in Northampton last year - discharged before the end of the evidence for legal reasons.