Supposedly it was cross-verified by several sources: A TV station in
England received about 22 minutes ...
This was in 1976 or thereabouts - more than two decades after the
broadcast. It has never been explained. I wish I could remember where I
read that...

I recall reading about that as a kid. I believe that it was in a book
called "Strange Stories and Amazing Facts," published by Reader's
Digest (I think) in the mid 70s. Pretty interesting reading, as I
recall.