So the answer to Friday's Mug-Shot challenge was James Bolam, which Heartbeatoz of Australia posted within twenty minutes after it went up. Pretty impressive.....
Bolam was seen as Roberts in a 1971 episode of 'The Rivals Of Sherlock Holmes' ("The Case Of The Dixon Torpedo"), which featured Jonathan Pryde as the rival of Holmes as an investigator.
Roberts worked for the inventor F. Graham Dixon, but at the same time he was working as a spy, stealing the plans for the Dixon torpedo and passing them off to a man named "Hunter" (or "Jaeger" in the man's original German tongue.)
Jaeger was an intermediary for the Russian spy agency of the time.
Although Roberts quickly changed his ways and helped set a trap for Jaeger, it's likely he went to jail. If so, he may have left behind a baby daughter (although he was likely not married, if you catch my drift. Nudge nudge. Wink wink.). That little girl could have grown up to marry a respectable man by the name of Halford and had a son named John. But throughout his life, John Halford would be known as "Jack".
Jack Halford became a police detective, retiring after his wife Mary was killed in a hit-and-run "accident". He later accepted an offer by the daughter of an old colleague to join her new team of retired detectives; they would investigate unsolved and closed cases (UCOS). It was during that new chapter of his life that Jack discovered that his wife's killer was a local gangster who had long been one of Jack's adversaries.
So that's the theory of relateeveety - Roberts is Jack Halford's grandfather. Of course, it could that Jack Halford's grandparent was instead Maggie Roberts, Roberts' sister, who got him his job by being fast and loose with her charms on Old Man Dixon.
If so, she could also have given birth to a son, named Halford after his father, and he'd grow up to be Jack's Dad. Either way, the family tele-genetics would be strong enough to repeat from grand-uncle or grandfather to Jack Halford.