... and eventually falling out? A simple and obvious means would be for the fishplate on one side to be tapped, so that the fish-nut could be locked against it. But I've never been able to find any reference to such an arrangement. Also, are all 4 bolts left loose? Or only the 2 on the switch rail? Or the 2 on the fixed closure rail? Or the outer 2, with the inner 2 adjacent to the rail ends being tight? Or vice versa? Here's another pic: 2_152217_590000000.jpg Looking at 8 o'clock in the picture, I think I can see the top left corner of the fishplate projecting away from the closure rail. Which suggests that the fishplates are bolted tight on the switch rail on the right, and are free to move on the closure rail on the left. But despite much searching I've never been able to get definitive answers to these questions. Here is C. J. Allen on the subject, in 1915: 2_071630_310000000.jpg Which is remarkably vague, given how much precise detail he usually ...