Hotblack Desiato is a minor character in Douglas Adams' Hitchhiker's Guide to the Galaxy, named after a real life real estate agency in Islington, UK:
Hotblack Desiato is the ajuitar keyboard player of the rock group Disaster Area, claimed to be the loudest band in the universe, and in fact the loudest sound of any kind, anywhere. So loud is this band that the audience usually listens from the safe distance of thirty seven miles away in a well built concrete bunker. ... The character is named after an estate agency based in Islington, with branches throughout North London; Adams said he was struggling to find a name for the character and, spotting a Hotblack Desiato sign, liked the name so much he "nearly crashed the car" and eventually telephoned to ask permission to use the firm's name for a character. Apparently, the firm's staff later received phone calls telling them they had a nerve naming their company after Adams' character.
Link [wiki] | The real estate agency