Thank you for your input on this work, and for this write-up; and to Stuart Langridge and others in the linked discussions for their insights. A few additional points: There are apparently just over 38K such images (taken by the RAF before 1st June 1957, so out of copyright) on Historic England's "Aerial Photo Explorer" site Historic England have refused to supply me with high-resolution copies of these images in response to my FoI request - https://www.whatdotheyknow.com/request/raf_images_on_aerial_photograph - because they are "reasonably accessible" to me; in other words, by me buying them at a cost of £12 plus VAT - EACH. Over half a million quid for all of them! How denying the public easy access to and free reuse of these out-of-copyright images meets Historic England's purpose to "[help] people care for, enjoy and celebrate England's spectacular historic environment" is not clear. Other organisations also use SmartFrame to prevent members of the public from downloading images of out-of-copyright artworks. Tate ("Our mission is to increase the public’s enjoyment and understanding of British art...", for example While copyright in more recent works should of course be respected, there are legitimate exceptions - https://www.gov.uk/guidance/exceptions-to-copyright - to UK copyright law (such as study, review or parody, etc), where copyright images may legally be downloaded and used (usual "I am not a lawyer" caveat applies). Downloading images whose copyright has expired is not "theft"