I don't think the GP comment was asking a question in a parenthetical; rather, they were expressing the names of both shows together using regular-expression syntax.

Makes sense. In my case, I probably would have phrased it as a question myself, since I did watch them as a kid but honestly couldn't tell you which one of those I used to watch.

True, though GP made a subtle mistake in not moving one space into the optional capture group. It should have been for example /Yes,( Prime)? Minister/, lest it were to match

    Yes, Prime Minister
    Yes,  Minister

Thank you Bernard. That will be all

No, Bernard. That question was purely rhetorical.

Source?

It's true, it was regex-ish. I did actually think about the space and decided it didn't look nice. It should also be clear from context clues (ie having declared watching the show and quoting it, familiarity with the two show names could be inferred). Plus you don't need parentheses to insert a question mark:

    Yes, Prime? Minister

Although if you're inclined to believe that's still regex the e is optional.

Perhaps it would've been clearer as:

    Yes,{ Prime|} Minister

rather than:

    Yes,( Prime)? Minister