Just as a matter of interest, is there an easy way of working out harp size?
Manufacturers (when they bother to tell you) often just give the distance from the needle to the upright part on the right, which isn't really enough, because you need to know how high the space is as well. They do sometimes give both dimensions. This machine is 7.5inches by 4.5inches, so the area is 33.75 square inches. My Pfaff, whcih is supposed to be a specialist quilting machine, is 7in x 4.25in, which is 29.75 square inches. That is, as far as I can see, top of the standard range for an ordinary machine. I suspect vintage machines tend to have larger spaces.
Of course machines are curvy, so the calculation is relatively vague anyway...
BTW, when I asked the British Sewing Centre live chat how big the harp space was, they didn't know what I meant.
@Snowgoose, that course looks brilliant!