Her death brings the Prime Minister out of his stupor, inspiring him to finally address the crisis.
So was that really the case back in the 1950s? Did Venetia Scott actually exist? Well, no.
The earnest secretary who memorises Churchill's autobiography and struggles through the smog to work is actually one of The Crown's few invented characters, adding a dose of warmth to a chilly Downing Street. Her life and death are both fictional.
The Great Smog itself was certainly a real event, though. London was enveloped in a blanket of thick, poisonous smog for several days, leading to thousands of deaths and overburdened hospitals.
But the "pea-souper" was less of a political crisis than The Crown makes out, so a dose of Venetia Scott adds tragedy to what was otherwise a devastating but undramatic event.
You might recognise Phillips as Wolf Hall's Jane Seymour, or remember her from her roles in Peaky Blinders and War & Peace – but it will be hard to forget her all-too-brief stint in 1950s Downing Street, dodging Churchill's bathwater...