It's definitely a Verdala bowl. :thup:
They come in different sizes - I've got Ming one@ 8.25" diameter, a red and blue strapped one @ 7.75" and a "seaweedy" one @ 10".
Ming and the red and blue strapping are post-Harris - you really have to go by the colours and patterns - this (to my eyes) red and blue is what Mark refers to as orange with applied green/blue, and, as he says in his book; "Michael Harris: Mdina Glass & Isle of Wight Studio Glass", p.53, "All pieces with orange bodies date from the late '70s on...". I would think that there is a possibility that a Verdala bowl may be late '70s rather than well into the '80s.
However, I don't think they're that scarce.
(heehee, but I think my seaweedy one is!)