Perhaps surprisingly to some, the actors portraying Rhys' parents Melanie (Mel) and Steve, are both actually Irish doing a "Liverpool accent". Considering the history of Liverpool and Irish (Roman Catholic) moving there, that may have been a deliberate casting choice with their ability to do a suitable accent, are accomplished-enough actors with the gravitas to carry the roles, and they both look enough like Rhys' parents to carry the series along.
In 2020, the international distribution version of the series, which ITV distributes themselves, was credited simply as "ITV Studios". Usually, ITV credits the bulk of their own productions, or their acquired programmes archives, to "ITV Studios Global Entertainment". However, as this is a serious docudrama, due to the nature of the story content, its understandable why they used their "serious" alternate name on this series.
When the Chief of Police asks Stephen Graham how he takes his coffee, he declines sugar with "I'm sweet enough." Graham was in Snatch with Alan Ford, who plays Bricktop, who also says "[...] I'm sweet enough" about taking sugar.