What is the test for "operating mind" in the context of an allegation of sexual assault made by a police officer?

There can be no doubt in the present case that the accused possessed a fully "operating mind" when he made the statement. He perceived the prospect of advantage in making statements he later said were untrue; the hope of advantage was not, however, held out by a person in authority. Nothing said or done by the police officers came near to offending the test for admissibility derived from Ibrahim v. The King.