Several detainees were systematically beaten, forced to stand still
for more than 24 hours, deprived of sleep and threatened with
unnecessary surgery or execution, the newspaper said.

Some are alleged to have been starved, subjected to extremes of
temperature, while others claimed they had been threatened with
electric shocks and menaced by interrogators with red-hot pokers.

The London Cage was installed in a row of mansions in the capital's
plush Kensington Palace Gardens, one of the world's most exclusive
streets. One of the mansions is now the London home of the Sultan
of Brunei.

The Guardian garnered the information from Britain's National Archives
and the Red Cross in Geneva, from which incidents at the Cage were
carefully concealed. 

The camp was run by Lieutenant Colonel Alexander Scotland.
Decorated for his interrogation of German soldiers in World War I,
he was called out of retirement in 1939 at the age of 57.

A report by MI5, Britain's interior security service, concluded
that Scotland had been guilty of "clear breaches" of the Geneva
Convention and that some interrogation methods "completely
contradicted" international law.

Scotland submitted his memoirs for censorship in 1950. An MI5
assessment found it detailed breaches of the Geneva Convention,
noting that prisoners had been forced to kneel while they were
beaten, stand to attention for 26 hours and threatened with
"an unnecessary operation" and execution.

A heavily edited version was published in 1957.

A letter of complaint from German SS captain Fritz Knoechlein
described his treatment after entering the London Cage in October
1946.

"Unable to make the desired confession", Knoechlein said he was
stripped and deprived of sleep for four days.

He claimed he was kicked, doused in cold water, pushed down stairs,
beaten with a cudgel, forced to stand by a gas stove with its rings lit.

The Guardian said he made the allegations while facing the death
penalty and could have been making a bid to escape the noose.

The Ministry of Defense is still witholding some of the papers on the
London Cage.