LOLOLOL!
I'd written myself into something of a corner and was struggling to find an exit strategy. Leaving this particular section to one side (a largely enforced break due to the Brooklands drawing office project) has definitely given me a fresh perspective.
Changing a character from being a neutral who doesn't know what's going on and has to have stuff explained to them just to move the plot along, to someone who becomes an antagonist because they smell a rat when some explanations don't meet their expectations suddenly makes all the difference.
And that way, my main character now has an antagonist in the present as well as in the past.