Foul as it is, Hell is made fouler by the presence of John

A man of forty-eight years, who had presided over the disintegration of the great Angevin Empire and brought the kingdom of England to its knees. A number of chroniclers confidently predicted that the late king would be condemned to Hell. One even added that: 'Foul as it is, Hell is made fouler by the presence of John,'

T. Asbridge, The greatest knight: the remarkable life of William Marshal, the power behind five English thrones (2015), 338

He is citing Matthew Paris, I think. This otherwise excellent book is marred by the absence of proper footnotes and instead their irritating replacement by textual references in the back