It is a bit confusing, both english frame makers, both made frames in the USA.
Witcomb was, and was until recently a small shop in London, and they are well covered on
the classic rendezvous website, in the british section and the us section.
Whitcomb aka Bill Whitcomb, was a framemaker from Liverpool, he started out as Harry Quinn's
apprentice, and stayed with Harry, until the rights to the Harry Quinn name was sold
in the late 70's. During this period Bill Whitcomb also did some building for Walvale, and Soens both
based in Liverpool.
After he finished with Quinns, he emmirgrated to the USA. He built and sold a small amount of bikes in the
states. After a couple of years in the states, he returned to the UK, where he built bikes under his own name
and for various bike shops. He also started back with Harry Quinn and his son, when they started up again
in Wales.
I have never ridden a Witcomb. But i own 2 bikes, built by Bill Whitcomb, both ride superbly very much in the Harry Quinn mold, they don't look flash, but if you want to cover ground quickly, they are some of the best.