I remember watching a documentary in 1990s that largely explained the phenomenon: it was basically that the human body became a candle with the body fat being t

I remember watching a documentary in 1990s that largely explained the phenomenon: it was basically that the human body became a candle with the body fat being the fuel and the clothing/blanket being the wick. I think they mentioned the alcohol in perfume or alcholic drink spilt could act as an accelerant. In their simulations with pigs they reproduced the effect, including the fire self extinguishing when it reached the unclothed ankles, leaving just the feet. Most of the cases were elderly or infirm wrapped in blankets or heavy clothing sitting in a chair by a fire.