These jars are marked "Kilner", and bear the Ravenhead glass makers mark on the base. Nothing wrong with that, except that they have no relationship that I know of with the French Le Parfait brand jars, which have that name embossed on the lid and body of the jar. I've only bought genuine Le Parfait brand jars before, and that not for a long time. The older Le Parfaits I have are thicker and heavier glass, with correspondingly thicker wire work, whilst these are altogether less "heavily-built".
It may be that newer Le Parfaits are similarly altered, but I don't know.We'll see how the Kilner model performs, anyway.
I can see where the problem arises. The French Le Parfait jars have always had this style of glass lid and spring latch, whereas the old Kilner jars had a metal 2-part screw-on lid with thin rubber seals. They went out of production, but have become now available again, branded "Kilner", and, at the same time, new Kilner marked jars (i.e. these ones) are on the market with the Le Parfait-style clamp closure and glass lid. All very confusing, but made worse by describing the product with two different names conjoined.