Mary Marshall
1842-1884

          the first British professional medium, through whom Sir William Crookes and Dr. Alfred Russel Wallace obtained their introduction to the phenomena of spiritualism. Her manifestations consisted of raps, movements and levitations of the table, knotting handkerchiefs under the table-leaf and writing on glass. This appears to have been a rudimentary form of slate-writing with which, in the later-known form, she also confronted her sitters some time after.

The first account of this demonstration was published by Thomas P. Barkas in Outlines of Ten Years' Investigations into the Phenomena of Modern Spiritualism, London, 1862. On a small scale Mrs. Marshall exhibited most of the phenomena of later mediums. From 1867 she held sittings for direct voice in which John King manifested. In her first séances she was assisted by her niece and occasionally by her young son. Her husband developed drawing mediumship.

Source (with minor modifications): An Encyclopaedia of Psychic Science by Nandor Fodor (1934).