The Gifkins jig seems to be quite similar to the old Stots's Dovetail Template Master, which has been copied or licenced by several other manufacturers, I think since the demise of Mr. Stots. It's still sold by Milescraft in the USA, but I'm not sure if it's available here.
https://www.milescraft.com/product/dove ... atemaster/
Stots's approach can be used either on a router table or clamped to the edge of the bench, and can be used to make secondary templates of indefinite length, and the "knit-one, perl-one" style of joint (with "missing" fingers). It will also do either box joints or dovetails. And it's really, really simple, with dovetail fit "adjusted" by use of paper shims or business cards!
I'm sure there are novel aspects to the Gifkins one, but my Stots template cost a very small fraction of the price. OK, it doesn't give as much choice of sizes, etc., but it was affordable.
The only issue I can see with the Stots one is the reliance on good bearing-guided cutters. For dovetailing the cutter must match the angle of the jig (eight degrees), and the bearings need to be spot-on. Finger/box joints basically just need a bearing-guided template cutter.
