We're therefore going to sell our existing one.

When we bought this, we gave it a good clean and put a rust treatment on it, before painting it with Hammerite metal paint. It's in pretty good condition now. We also bought a spare wheel for it, and have had 2 new tyres on it.
It'll carry one bike down the middle, or 2 bikes, one at each side quite easily. We've done about 8 or 9 track days, plus 2 op storm Wales trips with this trailer now, so probably 1500-2000 miles or so with it, not had a problem.
Looking for offers around £250. If anyone's interested, let me know. I am moving house next week, and if it's not sold by then, I will list on e-bay.