So what exactly is D"Abberville up to? SPOILER
First, when he meets with his handler to discuss getting more and final information for him from Toby's stuff before he disappears with a greal of money. Disappearing rich seems to be his plan.
Then, the next time we see him he's engaged to marry the Merry Widow. So, not going anywhere after all?
What's he up to? Is he afraid now that Toby is onto him and Toby's boyfriend also might tell Mi5 what he's up to, he decides in a panic to marry the mother of Lord Hamilton with the idea that if Toby causes a problem or he's otherwise fingered, he can hide behind the family title and get Lord Hamilton to intervene AGAIN to save him?
Is he banking Lord Hamilton and mumsy wouldn't want the scandal of her being married to a traitor, so they'll cover it up? So he's quickly marrying her after he realizes he's been found out?
What?