Yes, and he was quite widely respected in fact. He claims he was the first British historian to write about the bombing of Dresden (although he a notorious self-aggrandiser so take that claim with at least a pinch of salt).

I talk about David Irving briefly here. To paraphrase Irving "The Destruction of Dresden" was used by Kurt Vonnegut to write Slaughterhouse-Five.

Specifically Irving's Death toll of between 100 to 200 thousand was accepted at the time by most historians but has slowly been tapered down to under 50 thousand to as low as 20 thousand. But as stated for a time he was a respected historian whose numbers where used as fact by various institutions.