Rex Donaldson

In the novel Dumb Witness, Dr Rex Donaldson is Theresa's fiancé, and younger partner to Dr Grainger, in Market Basing.

Dr Donaldson is described as being of "medium height and of rather colourless appearance". His eyes are very pale blue and are slightly prominent. His manner is precise.

Dr Donaldson wants to go to London and specialise. According to Miss Caroline Peabody, he intends to specialise in serum therapeutics.

Theresa is attracted to Dr Donaldson because he is calm, detached and logical, and she also senses that there is "a secret force" in him, which is "masked by his unassuming slightly pedantic manner". Dr Donaldson's main preoccupation in life is his profession, and this heightens his attraction for Theresa.

During the events of the novel, Dr Donaldson comes to Littlegreen House for dinner. Emily Arundell wished to have an opportunity to study him at close quarters. However, she found him very polite, very formal, and intensely boring. She also disapproved of his decision to drink barley water, when she had opened a bottle of port for the occasion.

At the end of the novel, it is revealed that Theresa and Dr Donaldson get married, and Dr Donaldson makes a name for himself, becoming an authority on the functions of ductless glands.