Kennedy Design Studios recommend the following sites:

Thomas Messel ltd. A very fine furniture designer.

Richard Feroze. An excellent scagliola maker, mostly large columns and other architectural pieces.

William Horwood and sons. Engineering. Martin Horwood taught me all I know about lathes !

The Wikipedia page for scagliola. Contains some quite useful and interesting historical information.

Mcmarmilloyd ltd . A good gallery and resource of rare and unusual marbles.