Hi,

1. Ignore them (pity)
2. Upload them as public domain and re-iterate the National Portrait Gallery issue, and teach them that these open content wiki people are not to be trusted
3. Label them CC-BY so the Wellcome Trust can get a mandatory attribution, which we would do anyway

Personally, I'd go for #3. CC-BY is just one small step up from PD, so I really don't see the practical harm.

This is not the first time the Commons community deals with such a situation ; I believe standard practice is to use {{Licensed-PD-Art}} [1] which states both #2 & #3.

See for example its use for {{PD-Art-Yale}} [2]

(“Wikimedia Commons: there’s a template for that.”)

[1] <https://commons.wikimedia.org/wiki/Template:Licensed-PD-Art>
[2] <https://commons.wikimedia.org/wiki/Template:PD-Art-Yale>

Hope that helps,
--
Jean-Frédéric