That is indeed a factory top. On seeing VeeCee's earlier post the first thing coming to mind was: "A factory hardtop would be a good thing for that."
Factory tops aren't exactly Hen's Teeth" but a really nice one is hard to come by, especially if recently fitted with MacGreagor's seals 'n such. We've one purchased in 1971 and been on three of our MG's, wouldn't ever let go of it.