Richard Rich was totally a real life stereotype. And yes, it's amazing that no one on either side ever took revenge on him when they got into power. He really must have been amazingly useful, that's the only explanation I can come up with.

Cromwell in the Shardlake novels isn't a hero, but he is established as since about reform (which he probably was), and while Shardlake is disillusioned by him at the end of the first novel (when he realises that Cromwell faked evidence against Anne and her supposed lovers which he'd believed him incapable of), he never completely stops respecting him. I mean, even in Lamentation, he regrets having to burn the copy of Tyndale's bible translation which Cromwell gave him, and laments that men originally started in their career by Cromwell like Rich and Wriothesly are now gleefully working for the conservative Catholic cause. So all in all, I thought Sansom provides a plausible version of the man.