It requests an application/json response from the API at https://collection.sciencemuseumgroup.org.uk/search/images/?..., which returns metadata for an apparently random image (which may indeed be a 'never been seen' image, depending on what the backend does).
To save yourself seeing a blocky thumbnail before clicking through, just go to that API URL in your browser and refresh at your leisure.
Even better, change the value of the 'random' parameter so you can view more of these images at once:
https://github.com/TheScienceMuseum/never-been-seen/blob/mas...
It requests an application/json response from the API at https://collection.sciencemuseumgroup.org.uk/search/images/?..., which returns metadata for an apparently random image (which may indeed be a 'never been seen' image, depending on what the backend does).
To save yourself seeing a blocky thumbnail before clicking through, just go to that API URL in your browser and refresh at your leisure.
Even better, change the value of the 'random' parameter so you can view more of these images at once:
https://collection.sciencemuseumgroup.org.uk/search/images/?...