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