This, of course, raises the difficult ethical and moral issues surrounding the use of methods such as this to elicit information that might otherwise not be available.
The question being, are techniques such as these justifiable if they save the lives of an unknown number of innocent people?
While obviously a rhetorical question, the pragmatic answer is yes, they are, and it is difficult to argue against them except in cerebral terms of "violence breeds violence", therefore such barbaric methods cannot be tolerated in a civilised society.
The trouble here is that the people who would visit these random acts of atrocity upon innocent civilians are not civilised either and as such they automatically set themselves outside the parameters and mores that govern society. We live in an increasingly savage and disaffected world full of bitterness, resentment and fear.
If it takes the use of waterboarding (and other so-called "stress techniques") against those suspected of acts of terror to maintain the peace and security of the free world - and that includes the United Kingdom - then this is the price that we have to pay.
For our own security services to claim they do not employ these or similar methods may, depending on how they interpret "torture", be genuine. However, given the very nature of these services and their reputation for disinformation and duplicity, this statement must be regarded with suspicion; besides, in the interests of peace we should perhaps reflect on a quotation sometimes attributed to Winston Churchill: "We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm."