So, pre-Harold Saxon. Pre-the Minister of War. Pre-the moon exploding and a big bat coming out.
The Minister of War?
No, never mind. I expect I'll find out soon enough.
Alas, after the events of Before the Flood, we never did.
The modern series has all been about the foreshadowing. We've had Bad Wolf, Harold Saxon (Yana), Cracks in Time, the Hybrid, and the Timeless Child. The quizzically-concerned look on the Doctor's face when O'Donnell mentions "pre-the Minister of War" is akin to his reaction on hearing/seeing Bad Wolf during series one, and hers from The Ghost Monument, where the blanket audition rejects for an IKEA advert first mention the Timeless Child.
It could be one of those ambiguous subplots that is handily left for another writer/showrunner to use at some point down the time vortex. No doubt there are some (millions) of you who would rather have the Minister of War revealed as the Foundling instead.