You don't know that. For all you know, some kind of knowledge graph tag propagated too far. There is zero evidence of it being intentional.

You really think they'd just erase the photos of UK PMs? Please. If there was some kind of conspiracy there, don't you think hiding the information too (vs linking directly to the pages that have it) would be a more effective strategy?

I know it's fun to jump on Google as the dictator erasing history here, but have you really thought this position through? Especially when one of Google's big industries is education, and kids are going to write papers about WW2, and various British PMs?