Having tried to repetitively superglue the broken rubber bracket that fits into the front mudguard for securing the speedo cable, I have been looking for an alternative. Found this handy little stainless clip that seems to be doing the job OK.
I use a small Shouldered Stainless Eye bolt with rubber washers on the inner and outer wall of the fender, but your solution looks great. At least you don't have to un attach the cable and thread it through the eye, like my idea.