 Described as "an indefatigable ghost hunter", he wrote many books which surveyed alleged hauntings within the United Kingdom - beginning the trend of comprehensive regional 'guides' to (purportedly) haunted places.One of his well-known investigations concerned Borley Rectory, which he also wrote about.Born into a family who were Plymouth Brethren, Underwood had his first paranormal experience at the age of nine, when he claimed to have seen an apparition of his father, who had died earlier the same day, standing at the bottom of his bed.