The foster son of a woman branded Britain's most sadistic mother has revealed how she used to shove hot pokers and steak knives down his throat.

Christopher Spry, 30, suffered horrific abuse at the hands of his foster mother Eunice, now 75, over a 13-year period.

She systematically tortured him from the age of three, along with her other two foster children Victoria and Alloma.

Mr Spry, who lives in Gloucestershire, has been left in constant pain and battling mental health issues after she made him eat his own vomit and rat excrement.

In a new documentary called My Mother The Monster, he says: 'I don't really know why Eunice did all this stuff to us, all this abuse.

Christopher Spry, 30 (pictured left) suffered horrific abuse at the hands of his foster mother Eunice (mugshot right), now 75, over a 13-year period

'I don't think she was insane, I don't think she was particularly mad, just evil. Just pure evil.'

He tells the documentary how she used to force sticks, knives and even a machete down his throat and that he is now terrified of going to the dentist because he suffers flashbacks.

Medics found a small part of a metal blade lodged in his jaw where the Jehovah's Witness had attacked him with a knife.

Spry, who was released from prison half-way through her 14-year sentence in 2014, would beat the three children with a chair leg at their remote farm in Tewkesbury.

She would often starve them and on one occasion locked them naked in a room with nothing for a month.

Christopher Spry's hand is pictured covered in blood after suffering horrific abuse at the hands of his foster mother, Eunice

Mr Spry and his siblings would have to go without water for three days at a time and were left starving for a week.

As punishment for misbehaving, she would also beat them on the soles of their feet and force them to drink washing-up liquid and bleach.

She was initially jailed for 14 years for her crimes in 2007, but had the tariff reduced to 12 years by the High Court and was released in the summer of 2014.

Her children were outraged the following year when photographs emerged of her out shopping.

Mr Spry, who is now a youth worker and married to his wife Emma with whom he wants to have children, suffers from post-traumatic stress and often sleeps for just three hours a night because of the impact the abuse has had on him.

He is in constant pain, walks with a limp, and is getting treatment for scars that have turned cancerous.

Pictured: Christopher's sister Victoria Evans, who also suffered terrible abuse

Spry, who committed the offences between 1986 and 2005, also abused two other children in her care during the 19-year period.

She staunchly denied all the claims made against her and insisted the only physical punishment she ever used was 'a smack on the bottom'.

But a jury at Bristol Crown Court convicted her of 26 charges, ranging from unlawful wounding, cruelty to a person under 16, assault occasioning actual bodily harm, perverting the course of justice and witness intimidation.

At the time, Judge Simon Darwall-Smith told her it was the worst case he had come across in 40 years in law.

He told her: 'Frankly, it's difficult for anyone to understand how any human being could have even contemplated what you did, let alone with the regularity and premeditation you employed.'

The abuse was finally discovered after a Jehovah's Witness secretly confronted Victoria about marks to her head caused when Spry rubbed sandpaper over her face.

After managing to escape the house in 2004, aged 19, she then plucked up the courage to report her foster mother to the police.