The quick-fire show condenses all seven books in author JK Rowling's franchise – roughly 3400 pages of dragons, potions classes, Quidditch matches and world-saving duels – into just 70 minutes with just two performers on stage.
Clarkson and Turner were once the only performers, with Turner taking on the role of Harry while Clarkson portrayed everyone else, but their continued success means the show has grown beyond the pair. There are six alternate performers keeping the show alive, two of whom are heading to Auckland for a return season while the original stars debut Potted in Vegas.
Clarkson has a theory on why it's so popular: "I'm sure everyone's running to see myself and Jeff," he deadpans. The real answer? "I think with any parody, people come for the title but the content and the material has to be there to sustain it. It really is a big Harry Potter love-in."
Of course, the two creators are far from alone in their adoration. Despite the last book coming out 12 years ago, there are still millions of fans around the world breathing fresh life into the now 22-year-old franchise.
"It shows the power and effect Harry Potter has had over the world. I don't think this franchise is ever going away," says Clarkson.
Undoubtedly, given the huge financial drive behind the magical juggernaut. Theme parks, plays, studio tours, a second film series and re-released books every few years; Harry is as powerful now as he ever was.
But it was only three years ago that Clarkson finally met Rowling herself – "I swear she floated into the room" – though one plucky box office girl prevented an earlier meeting at Potted Potter's Edinburgh Fringe Festival debut.
"There was a story that a woman similar to Rowling came and was turned away as it was sold out. The manager of the theatre came and said 'I think that was JK Rowling'," Clarkson recalls. "We were never sure until I met her and she said 'I came to see the show but got turned away'. So now, wherever we are in the world, we have one seat we will always keep free in case she happens to come to the theatre."
How long Clarkson will be around to see that day remains to be seen. He and Turner are moving further into their 40s, and Clarkson admits it's becoming harder to convincingly play a teenage wizard, but as long as he can still do it, he has no intention of hanging up his wand.
"I'm not sure any other acting opportunity can top this. It's just so much fun, you have to keep reminding yourself this is what you get to do for a job."
Lowdown
What: Potted Potter
Where & when: ASB Waterfront Theatre, Wednesday April 17 to Sunday April 21