Re: London gang nominal?
> In Canada it's "Known to police."
> A clever euphemism for "he's never been arrested, charged, or convicted of any crime, but trust us, we know he's a criminal."
On this side of the Atlantic, it's someone with a criminal record, or a long arrest sheet or someone who keeps showing up associated with known criminals and their activities.
Such people are the first stop when searching for stolen goods, as a f'instance.