That old UT belongs to
the eight paperbacks that started my JRRT collection in the 1980's, possibly found in a single haul - also possibly with surprise on my side along the lines "I didn't know JRRT wrote that much!" As these include TH, a three-volume LoTR, the Sil, and BoLT 1&2, aka HoMe 1&2, I did then notice that half of them were edited by Christopher.
The spines of my paperbacks of HoMe vols 1 to 11 (12 is a Houghton Mifflin hardcover) show the changes in ownership in what used to be George Allen & Unwin, to which those eight black-jacketed
books belong:
HoMe vols 3 to 6 (LoB, SoMe, LR and RotS) are Unwin Hyman, but still Unwin Paperbacks;
vols 7 to 8 (ToI and WoTR) are Grafton, an imprint of HarperCollins, apparently because the hardcover originals had still been published by Unwin Hyman;
vols 9 to 11 (SD, MR and WoTJ) are then HarperCollins.
And that by now famous JRRT monogram first appeared on vol 7.