I, too, have heard of these frames and am interested in acquiring one of them. Whitcomb Lightweight Bicycles were built in England, that is about all I know right now. They are harder to find than the Holdsworths or Woodrups. http://www.witcomb.eu/
The frames, here, look spectacular.
There is a Wikipedia entry for Witcomb Bicycles, and at the bottom of the page, is a link to Whitcomb Bicycles. I do not know why there is a difference in the spelling. If you find out anything, can you let me know?