Here is the only fair way to describe Irving in the lead paragraph: 

 :David John Cawdell Irving (born 24 March 1938) is an English writer,[1] who specialises in the military and political history of World War II, with a focus on Nazi Germany. He is the author of 30 books on the subject, including The Destruction of Dresden (1963), Hitler's War (1977), Uprising! (1981), Churchill's War (1987), and Goebbels: Mastermind of the Third Reich (1996). 

 The second paragraph can then say that he is an adjudicated Holocaust Denier, etc. To insert Holocaust denial into the second sentence, only to immediately come back to that subject in the next paragraph evidences undue zeal and suggests too strongly that the article is intent on blackening Irving’s reputation rather than describing it.