I was Orderly Officer on several occasions and even those incarcerated in the Regional Detention Centre (RAF) were known as inspecting those on 'jankers'.

Not rhyming slang as far as I know it. My dad was a Station Warrant Officer (SWO) which was related effectively to an RSM in the Army and was Discip. He always referred to 'jankers' and he joined up in 1933, so it was in common use then.

Contrary to commonly held belief, as a SWO, he did actually know who his father was . . .