Same as a Moulton (which has bronze Oilite bushings) - there has to be some clearance, or it wouldn't move. The dimlles you can see in the nylon are for retention of grease but goodness knows how much is left of them after reaming. The Moulton design is much easier to overhaul but doesn't necessatily last longer. Something with taper roller bearings would be nice, but I suppose the factory can't work to that sort of precision.
Also learnt that the whole arrangement is imperial: the spindle is 3/8", the correct allen key for the bolts is 5/32", NOT 4mm, and the recommended tap for getting out the old bushes is 7/16" x 20tpi (a bit bigger than the M10 most people have, and will get more purchase on the bush). British engineering from the early 70s!