Hi John and Jillaine
Thanks for your responses.
My original reaction was to delete the image and send a message to the person who uploaded it asking them not to add images to profiles of which I am the manager, especially without properly sourcing them, because I don't live in the USA. The image is tagged PD-Art and this page says "there may be local laws that prevent or restrict the reuse of such images in your country" and then goes on to say it's not OK in the UK and inconclusive in Australia, where I live.
The image uploaded was the thumbnail from a Wikipedia article which had writing on it that I couldn't read. When I looked at the original image at Wikipedia, although the description says there is "a paragraph of indistinguishable text", I found most of it perfectly legible, so I removed the copy of the thumbnail and uploaded the image from Wikipedia Commons and added a comment what the text says, and the link and attribution supplied by Wikipedia Commons when you click "use this file on the web", which says "Attribution not legally required".
I did check the National Portrait Gallery and it is not one of their images, although the attribution provided by Wikipedia Commons is the attribution provided for an image at the NPG - not the one linked to on Wikipedia Commons but another image which is a copy of the original - another reason not to rely on Wikidpedia.
Jillaine, I had already read the previous questions. I decided to post this question because I'm too am HUGELY concerned about the lack of sources on WikiTree and I thought the more questions we have raising this issue the more likely there will be a change in sourcing requirements for images and maybe an updated styleguide/policy.