Roadster now up on axle stands, waiting for the replacement tie rod to arrive from MMC next week. Removing the two broken halves was simple. I was surprised to find that the outboard nuts were both finger tight - perhaps because the tension has been released? Anyway: I can detect no "collateral damage", so will fit the new rod and then drive the 20 miles to Berrybrook for an alignment check. Hopefully my fears of need a new crossframe will be allayed!