Being an accredited reporter (i.e CBC, CTV, BBC, etc.) gave you the freedom to interview almost anyone you cared to approach. This also true if you were a lowly freelancer, as I was for many periods of my life, providing say you are doing the interview for a well-known broadcaster even if that broadcaster has not  given specific authorization.  It was the "golden age" of freelance broadcasters, men and women traveling the world in search of stories.  Much of this came to an end with the introduction of public affairs programs based on telephone interviews. In Canada, programs such as "As It Happens" and "Radio Free Friday" were pioneers in the style of programing.  Instead of sending a freelancer to Paris or Berlin, of where have you, the "As It Happens" producer would go straight to the source, bypassing the freelancer on the way.

Although in those "golden" years (roughly the 1960s) it was fairly easy to talk to anyone you wanted to I did get rejections or turn-downs for interviews. Here are a few I remember.

george raft
George Raft
As I recall,George Raft was in London promoting some sort of entertainment/gambling venue. Because alleged mob connection British authorities turned him and his backers down (I think).  In any I phoned Raft from the CBC freelance office located in the former Langham Hotel and ask for and radio interview.  His response in that familiar gruff Raft voice was "No".  So I never got to meet on my favorite movie stars.

James Mason
Set of movie "Lolita".

alex guiness
Alex Guiness
Back stage of (tented) Stratford, Ontario festival.
Richard Conte
Richard Conte,

Bernard Montgomery

Bernard Montgomery