Advised https://twitter.com/TolkienFairy to join the site via Twitter and am pleased that Tolkienfairy is now a member.

On her website, https://tolkienfairybookmother.wordpress.com/books-im-looking-for/, Tolkienfairy talks about this edition,

clothbound_tolkien_boxset_tomdruil.png

Everyone would love to have the set shown above — or even just one of the books — for their collection! These clothbound hardcover books were released in a box set in 2013 from HarperCollins Publishers, but due to their limited availability, they usually go for a hefty sum (if they can be found at all). ISBN: 0007522932. ISBN-13: 9780007522934 (thanks to @tomdruil for sharing this sneaky ISBN number).

I asked HarperCollins about this set and this is the reply

8,000 boxed sets were produced; roughly half stayed in the UK, half went to overseas territories. The manufacturing cost of the slipcase far exceeded expectations (more than the combined cost of the books themselves) and it was decided that a reprint was unaffordable.

With declining sales, the individual Lord of the Rings volumes in that binding were discontinued too. They had been designed primarily for a Waterstone’s promotion, which once over meant that the ongoing orders were too small to justify continued print runs. There are so few retail channels now that we are increasingly at the behest of specific retailers, especially for titles with multiple editions, and these were never intended to be a permanent fixture in our catalogue.