MI5 officers tried out truth drugs

The intelligence service considered slipping benzedrine sulphate, a form of amphetamine, into food given to captured sailors and airmen in the belief it would render them garrulous, according to the secret papers. In behaviour reminiscent of syringe-wielding Nazi scientists, officers acted on a tip-off that the drug had been used by US police to extract confessions.

A memo sent to MI5 by a former US intelligence officer, Edward Whiteley, said: "It enables the British service to get information voluntarily without undue coercion. It takes 10 minutes for this to become effective and a 'talking spell' lasts for about half an hour."

The documents show that British interrogators had already experimented with the drug to judge its efficacy, and did not share American enthusiasm for it. One MI5 interrogator wrote: "I tried a compound of the drug but the effects were deleterious temporarily to the body rather than to the mind."