I'd say the canton and main ninian were pretty much the same as normal. The corner between canton and ninian is normally completely empty was much more full. The family stand is normally totally empty but was well filled out yesterday so any increases were due to there.
It was only 3k bigger than the Sunderland attendance (which didnt feel full at all) and those 2 things in consideration I'd say that's about right.
The blue seats in the Premier stand looked all full also and not sure if that's normally the case.
But yes in terms of people in the ground probably wasn't much more than 20k if that. I know many season ticket holders who barely make half the games and in fairness to the club the low prices for STs still make that worthwhile. And Sunday midday on sky with nothing to play for plus raining and no trains not a surprise if some decided to stay home (eg I get the train from barry but that was literally impossible yesterday as no trains at all so I had to find another way).