The wick theory states that SHC is actually perfectly explicable due to an understood process similar to that which burns a candle. According to this theory, a source of ignition applied to clothing can create an effect whereby fat from the body is drawn into the clothing - causing it to burn long and slow in the manner of a candle. Given sufficient time, it is argued that this long, slow burning is sufficient to render a body to ash - particularly if it takes place in a poorly ventilated room. After the program's broadcast, many criticisms were made of both its tone and presentation. These are perhaps most compellingly and comprehensively detailed in Spontaneous Human Combustion, by Randles and Hough.
The wick effect was demonstrated much more comprehensively on a second episode of the program broadcast in 1998, in which a whole pig carcass was used.