Patience
The young messenger who arrives at the teahouse is so uncomfortable with this particular missive's destination that he will place it in the hands of the first person he sees within, and dart off without even lingering to see if he might be offered a tip. The letter itself is simply folded, and written in a hand that attempts to be neat and steady, but manages to fall somewhat short of both.
Lady Swinton,
We're coming! I asked and it wasn't bad at all. I didn't know when to say, so could you tell me what night would be best for you? There is more, but I'd rather not write it.
Patience