Science Officer Buchan was the third most intelligent crew member aboard the JMC mining spaceship Red Dwarf (I.Q. 169), behind Flight Coordinator McQueen (I.Q. 172), and the ship computer Holly (I.Q. 6000, at least originally). Buchan was the foremost scientific expert aboard Red Dwarf.
Three million years later, Buchan was revived, or at least his scientific knowledge, in an illegal Mind Patch with the hologram Rimmer, as well as that of McQueen's mathematical knowledge. The Mind Patch was performed by Kryten to help Rimmer become intelligent enough to join the Enlightenment.