Whose voice was dubbed in for Flash Gordon?

Question

In the 1980 film Flash Gordon, the lead actor, Sam J. Jones playing Flash Gordon himself, departed from the project before post-production, leading to many of his lines being dubbed over by another actor. According to this interview with Jones (emphasis mine):

I didn’t have a falling out with the director, but producer Dino De Laurentis and I bumped heads a few times - there were a few misunderstandings. In my naivety at the age of 25 I just let the attorneys handle everything - I just let my representation handle it and they did not do a very good job at all. The bottom line, though, is they worked for me and I take responsibility for what happened. I didn’t go back for looping and dubbing so they ended up using another actor to loop - I think about half the film was actually not my voice.

So if it wasn't Jones's voice, whose was it?

Whose voice was used in dubbing for the character of Flash Gordon?

_{This question was inspired by our Flash Gordon movie night in chat.}

Answer 1

TL;DR: We don't know.

Wikipedia says that the voice actor's identity is unknown, but cites the interview you quoted, which doesn't say anything about who that actor was or whether their identity is known:

According to a 2012 interview in Maxim, Sam J. Jones had disagreements of some sort with De Laurentiis and departed prior to post-production, which resulted in a substantial proportion of his dialogue being dubbed by a professional voice actor, whose identity is still a mystery.

Director Mike Hodges said:

I was very fond of Sam but here's what happened: we did the main shooting up until Christmas and then we stopped for the break. After Christmas I came back and did all of the second unit stuff too. For instance, I had to do the shots with the flying men and that sort of thing—what passed as special effects back then (laughs). So I also had to shoot a whole bunch of other stuff with a stunt double for Sam and I had to re-voice the occasional line of dialogue too. Not much but some—and I got somebody to impersonate Sam's voice. You would never know it wasn't him.

But Sam found out and I think that was one factor that led to him being upset. And Dino and he just did not see eye to eye for a while. So when you lose your main star there can't really be a sequel.

An article in Empire Magazine doesn't help much (emphasis mine):

Director Mike Hodges keeps the pace cracking and shoots the whole piece from the crazy angles and in the lush colours of the original comic books. Queen's rock operatics deliver a score which is almost unique in being utterly inseparable from the success of the movie and Jones, now residing in DTV hell, deports himself admirably as the golden space boy - even if 80 per cent of his lines are dubbed by a still undisclosed voice.

Nor does TV Tropes, which also confirms the fact that the voice actor is unidentified:

On Flash Gordon, Sam J. Jones' voice was overdubbed by an uncredited actor whose identity remains a mystery to this day after Jones refused to return for post-production.

Answer 2

After watching some clips, I firmly believe the voice belongs to Peter Marinker, a prolific dubbing voice actor at the time. Compare some of his other voice samples;

It's speculation, but am I crazy?