Some of the discoveries in the archive will be finding their way into a forthcoming books chapter, but I'll mention along the way that Boston as revealed in her correspondence is a more acerbic personality that that conveyed by Mrs Oldknow, her fictional alter-ego in the Green Knowe books (although even Mrs O is capable of asperity). She's also a bit of a snob, though this is less of a surprise. That said, she spends a lot of time around the period she wrote her memoir, Memory in a House (1973) wondering how much she could in conscience a) embroider the facts to make them more interesting to read, and b) tell stories about her friends that showed them in a bad or ridiculous light, which is of course much more entertaining than 200 pages of encomia.
She also relates attending a function held in her honour in the week of her 80th birthday in 1972, only to find - as the photographer from the local paper lined them up for a publicity shot - that her bottom was being very thoroughly groped by the ancient chairman of the literary society. This took the gloss off the occasion (and no, she doesn't seem to think that because it's the 1970s it's perfectly normal and to be expected).
There are some interesting false starts and revisions among her manuscripts, but interestingly the chronological contradiction I noticed when recently re-reading The Children and The Chimneys (respectively) of Green Knowe, appears to have been there from the beginning. (In short, Tolly is only seven in the first book, but nine in the second, even though it's set only a few months later.) Whether it's an error or a deliberate inconsistency is a different matter.