A movie — for instance: Red Joan, which inspired this comparison — need not be produced by either studio — for instance: Red Joan isn’t — to be labeled as one of the two — for instance: Red Joan IS a BBC Film gone wrong. These classifications describe the content of a movie — for instance: you get the idea — specifically the signature aesthetic of each, more than who’s responsible.
BBC Films is a stylistically reigned-in Masterpiece Theatre, with geographically-specific period pieces that revel in war-torn romances, illicit affairs, dangerous liaisons, FLASHBAAAACKS FOR DAAAAAYS, and tales of personal lives that intersect with Important Historical Events, all while relishing in tropes and trappings — of genre, of fashion, of place and time, etc. — drenched in delectable dialects (usually British) delivered by the Isles’ foremost luminaries (usually British) of the stage and screen.
Except, Masterpiece Theatre revels; BBC Films merely dabbles. Masterpiece Theatre relishes; BBC notes. Masterpiece Theatre drenches and is drenched; BBC tidily addresses and is tidily dressed.
On a macro level, BBC Films confuses self-seriously subdued theatricality with resonantly-nuanced drama, leaving little room for a personal touch that’s more than the workmanlike. How can such sterility possibly ignite any real sensuality in the aforementioned romances?
Cut to: the flaccid sex scenes masquerading as lusty lovemaking.
That’s a pretty accurate description of Red Joan as a whole, and the rest of its mediocre BBC Films ilk.