I had not actually thought of gothic novels as Regency 'pop culture' yet I believe this is a fitting idea for people esp. like the flashy Thorpes.
Isabella's converse revolves around fashion, flirtations, and quizzes to gain attention. She gives Catherine a list of seven new titles yet shies away from mention of 'Sir Charles Grandison', an old fashioned novel.

I think Delories makes an interesting point on newspapers being part of popular culture.
They were accessible to people of all classes. I imagine a paper reader like Mr Allan would discuss current affairs such as possibility of war with France, and new taxes with other gentlemen in the Pump Room and swapped round papers.
Similar to today, C18th papers reported - food price rises, government announcements, cartoons lampooning the government or Prince Regent, local fairs, plays, book reviews and short stories-all part of popular culture.
Yet there were sordid things reported in papers which were part of popular reading culture in 1800 - hangings ( carried out in public ) riots, court hearings provided entertainment for people of all classes from the public galleries.
Newspapers also reported fashionable arrivals in cities- at one time Henry fetched the newspaper from Bath to see if any baronets were arriving.
For the staff and family in a great house like the Abbey, newspapers must have been welcomed as a source of information and entertainment for both family and servents. Senior staff would be literate at least.
Another aspect of popular culture was fashion magazines such as La Belle Assembly. Possibly Mrs Allan collected these, but we don't hear about her reading habits.