I first thought
Written by MarianneR
(3/25/2009 12:14 p.m.)
in consequence of the missive, Ch.28: Who is Alice?, penned by Line
it was a daughter of Lord Longtown´s and a close friend to Eleanor. But the footnote in your edition seems also possible - a maid servant might as well be privy to Eleanor´s secrets and be reliable enough to receive a letter on her behalf.