Bobby at RR Auction posted a reminder for this currently running auction:

Tolkien ALS at RR Auction

Description
ALS, one page both sides, 8 x 10, George Allen & Unwin Ltd letterhead, April 10, 1969. Letter to Mrs. Mrockzkowska, wife of Professor Przemyslaw Mroczkowski.

In part: "I live now in retirement and have endeavored to keep my address secret from the press and all other intruders who have made it impossible for me to do any more writing especially since I am now beginning to feel my age; all the more because of an accident last summer which crippled me for a long time and leaves me still rather lame…I have been overwhelmed with troubles of my own; my family that gives me much cause for grief and anxiety; my wife’s increasing ill health…and so on! Your daughter does not date her letter. Alas! She says her thesis must be presented this month (April). There is no time left in which I could give her advice or help that must be useful. I wish she could have plucked up the courage (as she says) to write to me sooner for I should have liked to help for her father’s sake. She writes a very good intelligent and perceptive letter. Indeed I think she displays more understanding than the ‘high authorities’ who altered her title…May I say that Poland for its own sake, but especially since it is your country, is ever on my mind. I pray for you daily, and your country."

Tolkien also adds a postscript along the bottom of the front indicating where personal letters should be sent so “they do not get lost among notes, manuscripts and other papers.” In fine condition, with intersecting mailing folds, a couple blue ballpoint notations, and a few trivial brushes to a few letters of text.

Letter from J.R.R. Tolkien to Mrs. Mroczkowska • 10 April 1969 (#809)