So I decided in the scheme of things to run around and do the Baron's quest lines first, thinking I could challenge him to Gwent afterwards and that stopping to play him at cards just wasn't in keeping with the tone of the mission itself. Wasn't to be. In my game, he found his wife in the swamp and took her off to a hermit and then I had to punch the snot out of some snotty seargent. Satisfying as that was, I did not play the Baron for his card.

Now, I DID play a little brat, who was supposed to be really good, and who had apparently even "beaten the Baron once". Is this a loophole so that we can chase the card after the Baron's quests are complete, or have I lost that card for this play through?

Any help would be much appreciated!

Take a look into your quest journal. It should say to look for the card and information on other players in the barons office.

Just found it there myself, to be exact.

You can still get the Baron's card, you must return to his house and search in his room.

N̶o̶,̶ ̶y̶o̶u̶'̶v̶e̶ ̶l̶o̶s̶t̶ ̶t̶h̶e̶ ̶D̶i̶j̶k̶s̶t̶r̶a̶ ̶c̶a̶r̶d̶.̶ ̶T̶h̶e̶ ̶c̶h̶i̶l̶d̶ ̶p̶r̶o̶d̶i̶g̶y̶ ̶g̶i̶v̶e̶s̶ ̶y̶o̶u̶ ̶R̶o̶c̶h̶e̶.̶ ̶I̶t̶'̶s̶ ̶n̶o̶t̶ ̶a̶ ̶l̶o̶o̶p̶h̶o̶l̶e̶. Oh, I didn't realise that. Post amended.

Ahh, that might have been it! I think I did that, but can't remember getting a card, just a list of people to play. Excellent, thanks!