Hi Stefan,
Your information is correct. Culp was interviewed first by the Andersens for the part of Cdmr. Koenig in SPACE:1999 - the role that eventually went to Martin Landau. (SPACE:1999 came out in 1975 - when 1999 seemed far into the future ... makes you feel really old, huh?)
Here's 2 articles that explain what happened.
Space 1999 Remembered - (the section about Robert Culp's interview) ...
http://www.space1999.net/~catacombs/main/crguide/vczga.html
and
Gerry Andersen: The Puppet Master 4 - with comments by Sylvia Andersen
This website gives lots of information on all of his projects - just go down to the SPACE:1999 section ... (I'll list the link at the end.)
Here is the part about Robert Culp's meeting with them from this article.
"Gerry’s next task was to find a US actor with a suitably high profile to attract the American networks where it was vital the series succeed. The actor he decided on former I, Spy star Robert Culp. Sylvia Anderson thinks that Culp would have added an extra dimension to the series: "I wanted Robert Culp. When we met him he was quite outrageous, but he would have given the series a very interesting angle. He would not have been the stereotyped hero; he would have been scared at times, he would have made the wrong decisions." However, Gerry’s memory of meeting the star was different from that of his wife’s: “He said ‘there’s something I have to tell you. I want you to know that I’m a great actor. Something else you should know is that I’m an even better director and an even better writer.” Gerry says that at that point he decided that Robert Culp was not going to be suitable for the series."
http://www.teletronic.co.uk/gerryanderson4.htm
(Umm .... Sure would have liked to have seen Bob in those form-fitting, space-faring jumpsuits they all wore. Alas, it was not to be!

)
As always,
Tatia
P.S. Didn't Kelly take care of Danny in Hong Kong??

or perhaps it was just "evening the score," because Culp got the far better role (not the fright-wig crazy part) in Shirley Temple Theater's "House of Seven Gables." (1960)
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