Re: London gang nominal?
"Nominal" in Britain is an adjective meaning "by name", roughly. In other contexts it seems to be a synonym for "normal". In the well-informed wizarding police procedural novels by Ben Aaronovitch, starting with "Rivers of London", in the 21st century "nominal" as a noun means anyone whose personal details are put in the police database in the course of an investigation; criminal, victim, witness, bystander, family members, anyone else who turns up in the book. After all, who has done what is only to be determined in the course of investigation. I presume it's also possible that Nominal 1 (mysterious wizard) and Nominal 2 (Mr P Daniels of television notability) turn out to be one and the same person, or somebody has an identical twin brother or sister. Pbzr gb guvax, gung'f unccrarq va gur obbxf. (ROT13)
It's slightly like "person of interest", except that that American phrase, according to its Wikipedia article, did in fact start out with meanings such as "someone that the police keep a file on because they're black", and presently tends to be treated by the public as "suspect / villain", although I gather the original point of the recrent television series titled "Person of Interest" was that an omniscient, prescient, literal Machine would tell investigators that somebody was important this week but not why.
I think the police would not tweet "this bloke's guilty and he won't go to the lavatory" and then expect a court to accept that a fair trial on the allegation is taking place when they've already publicly libelled him - so to speak. So, no, everyone's a nominal.