Born in the same year as flying saucers, 1947, he first learnt of them at the age of 7, when a UFO landing took place near his hometown, Diges, gaining front pages of local papers. That report instigated his early interest in science fiction. In his teen years, Bertrand visited René and Francine Fouéré at GEPA (Groupe de’Etudes des Phénomènes Aériens) and subscribed to its journal Phénomènes spatiaux, soon beginning to do field investigation on local UFO reports. A meeting with pioneer ufologist Aimé Michel was instrumental to address Méheust to philosophy studies. After graduating he has since been teaching philosophy, sociology and ethnology, and in 1997 got his  Ph.D. in sociology with a thesis about how normal science reacted to psychic research in the 19th century.

In 1978, he published his first book (Science-fiction et soucoupes volantes) on strong similarities between contemporary UFO reports and obscure science fiction novels of the early 1900’s.

During the ’80s he concentrated his studies on animal magnetism from the viewpoint of testimonies and had a second book (Soucoupes volantes et folklore, 1985) published on an ethnological parallel between alien abductions, visions and folklore accounts of otherworldy meetings.

An editorial board member of UFO journal OVNI Présence, Méheust was fascinated by the Belgian wave of 1989-90 and, caming to the conclusion that it could not be reduced to psycho-sociological explanations (Retour sur l'”Anomalie belge”, 2000).