... holding the chair down. That theory fell by the wayside after the grouping -- the GWR prevented movement by having saw-tooth serrations on the bottom of the chair, and matching serrations adzed into the surface of the sleeper. The spike hole is smaller than the screw/trenail hole, and the spike usually has a domed head, so is much less prominent than a screw. Screws were used with tapered wooden ferrules of similar size to trenails. Here's a drawing of a GER ordinary chair having 4 such fixings: 2_280655_550000000.png The curved sides on many pre-group chairs are quite noticeable. Other companies using similar 4-fixing chairs were the Midland (trenails), and the LNWR (screws, chairs with straight sides), and several others. It was a popular pre-group design. edit: thanks to Dave for the LBSCR info. I can post scans of the Midland and LNWR chairs if you wish? cheers, Martin. posted: 28 May 2020 12:08 from: Ian Allen Hi, Pre-grouping use ...