The British Free Corps was the Nazi’s attempt to recruit British prisoners of war into a Waffen-SS Unit. According to Wikipedia it was not much of a success,
Research by British historian Adrian Weale has identified 54 men who belonged to this unit at one time or another, some for only a few days. At no time did it reach more than 27 men in strength.
The unit was the brain child of British fascist John Amery, who was executed in 1945 for treason.
