Hereford, i make boxes out of spare tongue and grrove wood i have around. I make a box about 2' square, but i hinge the front piece so it opens like a door.
I start with two, one on top of the other, plant the spuds and then start earthing up, when they get full i add another one on top and so on.
Once i think the first of the spuds are ready, i open the hinge on the bottom box, and slide it out from under the others. before i aqllow the others to fall to the bottom, i scoop out the spuds that are ready, and whatever soil comes with them, then slide the remaining boxes down to ground level, and add the one i removed, back on top. Just keep going after that, til the plant has given it's all.
My soil is not good for spuds for some reason , so i grow them on concrete and slipp a black bin liner or some old carpet on the bottom to keep the grubs out that eat the fuckers.