:::The estate's intention may be to advertise and promote an exhibition, but do remember that (as long as the copyright is acknowledged properly) just about any reuse of the image is legitimate. (Exceptions include violations of personality rights of those depicted.) So for example if I have a copy of a book by PJG and I want to sell it on eBay, the CC licence lets me put as large a JPEG as I want into my eBay page  Here's just one example! On page 121 is this great photo (© National Library of Wales, Creative Commons Attribution-Share Alike 4.0 International license)  where of course my intention is merely to arouse more interest and thereby generate higher bids and thus more money for myself. ¶ When I say above "in order that the file does not run into trouble later", I have in mind my experience of deletions from Commons of photographs I've encouraged living (and published, exhibited, even fêted) photographers to upload, because (I later realized) this or that irritating requirement hadn't been met.