PX and the related WWII figs (many sculpted by Richard Ansell) are 1/48th scale (34mm-36mm), so they're too big for 28mm and too small for 40mm.
Not many companies in the 1/48th *minis* business -- Sloppy Jalopy, Tumbling Dice, Fox Miniatures (?), Rest Models, HLBS (modern), and Enemy Lines.
C'mon Nick! Who is it???