In the novel Destination Unknown, Dr Neilson is the deputy director of Aristides's research establishment located in the High Atlas Mountains. His is not a medical doctor. His specialty is administration and he takes charge of the admisitrative functions of the unit. Hilary Craven was taken to see him on arrival as part of his routine of interviewing all new personnel who entered the research station.
Nielson assured Hilary that she would be comfortable in the unit. It might feel claustrophic at first but he assured her this would wear off. There was a wide range of recreational facilites and provision for any artistic requirement such as painting, sculpture or music. If there was anything in particular she wanted, she only had to put in a request.
Hilary observed that Neilson was a "big, florid man with an urbane manner". He was probably of transatlantic origin, although Hilary could detect very little American accent.