The offender was an old lady, who was there with another old lady. Now, the non-reactor clearly had some “gnarled, useless ears” on her, because her audible friend had to repeat everything she said to her, which unfortunately included her reactions. So here is a choice selection from the screening (apologies for any slight spoilers):

“That’s got rid of him then” - during the Subway advert before the film started.

“He doesn’t look well” - the first time we see Wilberforce.

“Did you see that - how horrid” - the appearance of a slave girl in chains.

“He looks old” - unsurprisingly, when Wilberforce is older.

“How beautiful, my grandson plays the bagpipes” - during the final scene.

Not only was the cinema packed, so I couldn’t move, I was the only person in there who wasn’t drawing a pension. So imagine the dentures that would be hurled at me if I’d told her to shut it. And shooshing people doesn’t work if they’re either deaf or talking so much they can’t hear anything else.