Being frankness itself, she says exactly what she thinks, without the least regard for others' feelings.

If talk is (or seems to her) dull, she declares that she has had enough of it.

I don't think there is any need to warn you of this, but it may be as well that you should know it.
"Whilst I am writing, I had better mention one or two other peculiarities of Lady Ogram.

At the first glance you will see that she is an invalid, but woe to you if you show that you see it.

She insists on being treated by everyone (I suppose, her doctor excepted, but I am not sure) as if she were in perfect health.