Carpetsahib,
Sorry mate I can't give you a date but it would have to be late '80's early '90's from memory. Unfortunately PH no longer exists as far as firearms manufacturing - they were rather prominent here in Australia from the '60's onwards.
Again gong from memory it wasn't all that long after this came out that the company folded - so I guess that may help?
Sorry I can't help further
93x64mm