Sheldon Brown may be able to help here:
The Thorn has a Reynolds 531 steel fork, 1 1/8" threadless. I installed a conventional threadless stem for the drop bars, but I omitted the usual "star fangled nut" in the steerer and the cap that usually goes on top of the stem. Instead, I installed a wedge-type quill stem into the hollow steerer. This is a stem with a 1 inch outside diameter, intended for use with a 1 1/8" threadless setup, but it was a good fit.
http://sheldonbrown.org/thorn/index.html