In A and Others v Secretary of State for the Home Department (No 2)  EWCA Civ 1123;  1 WLR 414 in the Court of Appeal Neuberger LJ said at para 414:
… one of the principal reasons why a confession made by an accused is excluded from evidence unless it was voluntary is that such a confession is self evidently unreliable. That reason would apply with equal force to a statement obtained from a third party under torture.
In the same case in the House of Lodrs  UKHL 71; per Lord Carswell addressed torture and unreliability in the following words at para 147:
The unreliability of such evidence is notorious: in most cases one cannot tell whether correct information has been wrung out of the victim of torture … or whether, as is frequently suspected, the victim has told the torturers what they want to hear in the hope of relieving his suffering.