I see that a low angle jack plane will cost at least £115, although superior versions cost double.
This is very much an inferior version. But it works. I am glad to be able to use a Stanley Bailey 5 1/2 body, which I salvaged. All the parts had been removed, but the only fault I could find was a slight crack near the mouth.
I ground off the the part of the casting for fitting the frog, as best I could, lacking milling facilities, and made up a cherry infill wedge, of two parts,. The larger piece has the handle screwed to it and is secured to the base by screws through the sole. The smaller wedge, behind the mouth, is epoxied..
So, crude, but fairly effective.