This design comes in a few shapes I know of - this barrel, a tall (8") unstoppered bottle with straight sides and short attenuated neck bottles.
You really don't see much of it around. I believe it to be post-Harris, but from the period while Boffo and Dobson were still there, before Said took over and designs became a lot more simple and far easier to execute. It's probably Dobson design. I would put it somewhere between '71 and '77.
There are a few ranges from this period which are (IMNSHO) absolutely wonderful and well worth collecting - this one; the yellow splodgy background, with marvered in strapping of splodgy orange, one seen far more often - the red (often described as orange) streaky/cloudy background with blue (often described as green) strapping; and finally, one which is a Harris design, but was mostly produced after he left, the two-tone amethyst and blue pieces with thin clear strapping.
The base body is clear, but stuffed full of silver chloride crizzle, and blue strapping is applied externally. I can't really see too well from your pics that the body has the crizzled silver chloride effect... does it?