Mordred was completely without any legal status, and that people would consider him particularly a sinner because he was conceived in sin

Correct me if I'm wrong, but - didn't Mordred pass for King Lot's son? I'd have to check Malory again, but I don't think it is generally known at court that he is Arthur's son. Consequently, he had the status of the youngest Lothian/Orkney prince. (In Geoffrey of Monmouth, he really is Lot's youngest.) That places him well behind Gawain in the line of succession, but still, there are worse situations.

Cornwell's trilogy is pretty good - I'd recommend it too. I mean, it's not T. H. White-good, but it's a very entertaining read, with a great Arthur and a strong Guinevere (and a silly little Gawain, but... *g*).

I'm curious about The Winter Prince; I'll look it up.