That thread, wow.
And someone downthread posted the episode that's taken from.
Season 1, Episode 2 of Lewis: "Whom the Gods Would Destroy".
"DI Lewis and DS Hathaway investigate the murder of Dean Greely. As the investigation continues, they discover that Greely and three other men had formed a club during their Oxford student days, the Sons of the Twice Born.
Terrible subject, but a possible red-pill tool for those who love British mysteries.