Roddenberry's original pitch in 1964 features Captain Robert M. April commanding the S.S. Yorktown. The ship's name is first mentioned on page nine.Anybody here actually believe that? I don't. There's no evidence for it, at any rate.Yorktown. It was the Enterprise before she became the Enterprise.![]()
Background material doesn't count. Is there any overt evidence, as shown onscreen, that either ship (the TOS version or the Enterprise-A) was ever any other ship? I would say no.
Indeed, the fact that in the beginning of ST IV, the Yorktown was one of the ships that was heavily damaged by the probe, I would find it highly unlikely that it was rushed back into service so quickly. If anything, there MIGHT have been a newer, replacement Yorktown under construction, but which was renamed Enterprise-A before it was finished. But in a very real sense, then, that ship was never a Yorktown, it was always Enterprise - because that name is the one it had when it entered service.
As for TOS? It was already established that the Yorktown and Enterprise were separate vessels (in episodes such as "Obsession").