US police uncovered the torture chamber after a two-year investigation into a paedophile ring led them to the home of British-born Geoffrey Portway in Worcester, Massachusetts.

They found a staircase leading to a hidden, sound-proofed room containing a child-sized coffin, a steel cage, handcuffs, castration tools and a collection of knives.

Officers found stairs leading to the sound-proofed basement room

Portway had even drawn lines on a photograph of a young boy showing "the different cuts of meat", according to court documents obtained by the Boston Herald.

He has pleaded guilty to plotting to kidnap a child and to distributing and possessing child pornography and will be sentenced on Tuesday.

Sets of handcuffs were discovered in the chamber

Prosecutors hope he serves at least 27 years behind bars before he is deported back to the UK.

Federal officials wrote in the sentencing papers: "Portway has pled guilty to some of the most vile and heinous crimes known to our society, namely participating in the sexual exploitation of young children through the possession and distribution of child pornography and soliciting the kidnapping of a child for the purpose of killing and consuming that child."

Police also found a child's jumpsuit in the room

Portway used the pseudonym 'Longpig' - the cannibal name for human flesh - as he chatted online with other paedophiles about their desire to abduct, kill and eat children, the court papers revealed.

He was among dozens arrested in the investigation that began with the detention of another man in Massachusetts who has been jailed for 18 years.

Portway's house (Pic: Google)

More than 50 suspects were eventually detained and over 160 children were rescued in the US, Canada and Europe.

Michael Arnett, above, plotted the abduction with Portway

Portway solicited several people to help him abduct a child, including a man named Michael Arnett from Kansas.

Arnett has pleaded guilty to sexual exploitation of a child for the purposes of producing child pornography.