A mother who killed six of her children in an arson attack has been freed after serving half of her 17-year jail term.

Mairead Philpott, then aged 32, was jailed in April 2013 after being found guilty of six counts of manslaughter alongside her husband and another defendant.

Philpott, now aged 39, is understood to have been released on Friday from HMP Send in Surrey to a hostel, where she will be supervised while on licence.

Her husband Mick Philpott was jailed for life with a minimum term of 15 years after starting the fire at the couple’s home in Allenton, Derby, on May 11 2012.

Jade Philpott, 10, and her brothers John, nine, Jack, eight, Jesse, six, and Jayden, five, all died in the fire, while Duwayne, 13, died in hospital three days later.

The Philpotts appeared at a news conference five days after the blaze, in which they both sobbed, while Mick expressed disbelief at the deaths and thanked fire crews.

A trial at Nottingham Crown Court was told Mick Philpott was the “driving force” behind the plot to start the house fire, and had intended to frame a former partner.

Passing sentence, Justice Thirlwall said that six young lives had been taken due to “callous selfishness”.

The judge told Mairead, who was ordered to serve half of her sentence before release, that she believed her grief was real but she should not have put her husband first.

“These were your children; your first responsibility, surely, was to them,” the judge told the court. “Instead you joined in with his plan.”

Mairead later appealed against her sentence, but judges ruled the original term reflected the “immeasurable harm” she had caused.

Court of Appeal judges said petrol found on Mairead’s clothes showed she had participated in setting the fire, which had not been a “spur-of-the-moment” plan.

She had also lied after her arrest, the judges said, and continued to hide the truth during her trial.

The Conservative MP for Mid Derbyshire Pauline Latham said she was seeking assurances that the killer would not be permitted to return to the area.

The MP said in a statement: “I am disgusted that this foul woman has her liberty while her daughter and five sons lie in their graves.

“Eight-and-a-half years in jail amounts to her serving less than 18 months for each of those poor children. How can that possibly be right?

“Those in charge of making these decisions need to think longer and harder about the victims and the value of their lives.

“In addition, this horrible crime is still very raw in Derby and I fear what would happen if she turned up in the city.

“Therefore, I am seeking assurances that she will not be returning to the area.”

The Centre for Crime Prevention described the release as “appalling” and called for killers to serve their full sentences for such crimes.

Its research director David Spencer said: “The system of automatically releasing criminals like her half way through their sentence means that in cases like this justice is not being done.

“This needs to change. For crimes like these, those convicted need to serve their full sentence.”

The Sun on Sunday reported that the killer will be offered counselling and life coaching, and is set to be given a new identity at public expense.

A spokesman for the Prison Service, which does not comment on an individual prisoner’s release, said: “Offenders released on licence face strict conditions and can be returned to prison if they breach them.”