Last year his automatic release from prison was blocked by the Lord Chancellor after campaigning by Ms Simpson's friends and family.

The case is now the subject of a new ITV documentary.

So who is Brown, who was Joanna Simpson - and what did he do to her?

Who is Robert Brown and what did he do?

An airline pilot, Brown became known as the "British Airways killer" or "BA killer".

He killed his estranged wife Joanna Simpson in October 2010, attacking her when he was dropping their young children at her home.

He beat Ms Simpson to death with a claw hammer as their two children cowered in a playroom next door, hitting her 14 times.

Brown then loaded her body into the boot of his car, dropped the children at his house, and buried Ms Simpson in a makeshift coffin in a hole he had pre-dug in Windsor Great Park.

He called the police the next day to report a domestic incident but initially refused to cooperate with their investigation.

Brown told police he had been "stitched up" by a prenuptial agreement, which gave him no claim over his wife's trust fund.

The family home was also in her name, and the couple were due in court to settle their financial disputes and finalise the divorce.

What was he convicted of?

He was acquitted of murder by a jury at Reading Crown Court in May 2011, but was jailed having previously admitted manslaughter on the ground of diminished responsibility.

The court heard he had an adjustment disorder, a strong emotional or behavioural reaction to stress or trauma that can rarely lead to outbursts of violence.

Brown was sentenced to 24 years for manslaughter and a further two years for an offence of obstructing a coroner in the execution of his duty.

Who was Joanna Simpson?

Ms Simpson was brought up on the Isle of Man and went to Bath University, and later ran a successful 5-star bed and breakfast business in Ascot.

She was 46 when she was killed.

A foundation set up in her name supports children affected by domestic abuse and homicide.

The charity's website describes Ms Simpson's "strong moral values" and says its work is "based on her beliefs, values and the love of her children".

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Will Robert Brown be released from prison?

Because Brown was convicted of manslaughter - not murder - he was due to be automatically freed on licence halfway through his 26-year sentence, in November 2023.

But Lord Chancellor Alex Chalk intervened last October, using new powers to keep him in jail.

He said his "appalling case" would instead be referred to the Parole Board to decide if he is safe to be released.

"Joanna Simpson was bludgeoned and buried at the hands of Robert Brown, which left two children without a mother and caused irreparable harm to her family and loved ones," said Mr Chalk, who is also the justice secretary.

"I made a commitment to Joanna's family that I would give this case my closest personal attention.

"Having reviewed all the information available to me, I have blocked Brown's automatic release and referred this case to the Parole Board using powers we introduced to protect the public from the most dangerous offenders."

The move to block his release came after a campaign by Ms Simpson's best friend Hetti Barkworth-Nanton, and family, including her mother Diana Parkes, which was backed by Carrie Johnson, the wife of former Prime Minister Boris Johnson.

A decision on whether Brown will be released will be made by the Parole Board.