It isn't a serious engagement.

It was entered into by him in a most chivalrous manner, to save me from the consequences of a very clumsy attempt on my part to get back that packet.

But there it is.
Every one down at his home believes at the present moment that we are engaged and that I have come up to London to see our Ambassador." "If you are engaged," Fenn sneered, "why hasn't he told you more of his secrets ?" "Secrets!" she repeated, a little scornfully.

"I shouldn't think he has any.

I should imagine his daily life could be investigated without the least fear." "You'd imagine wrong, then." "But how interesting! You excite my curiosity.