(66)have a private down on …
It was almost as though he had a private down on the fellow.”

「have a private down on …」で「・・・を個人的に憎んでいる」の意。

(67)at all
“Did you know Seton at all?

「at all」は疑問文では「いったい、そもそも」の意。

(68)get a bee in one’s bonnet
“There there, my dear. Of course it’s not true. Fellow’s a madam. A madam!
Got a bee in his bonnet!

「get a bee in one’s bonnet」で「妙な考えにとりつかれる」。

(69)get hold of the wrong end of the stick
Got hold of the wrong end of the stick all round.”

「get hold of the wrong end of the stick」は「物ごとを完全に誤解する」。

(70)get up
“English roads are hopeless, of course.
Can’t get up a decent pace on them.”

「get up」はここでは「を増す」。