On Sunday I took some photos of the bike trailer, did a bit of work mending bits, then tried it out for the first time (taking a box of plastic bottles round the corner to the recycling collection point, and glass to the bottle bank (why can't they be in the same place?)).
It shimmies badly. Bought a couple of rivnuts at Mackays this morning, which I think I can use to improve the sloppy joint. Longer term I think it wants a hitch more like this.