gpg 2.x or gpg 1.x // is there a way to tell which one was used from the encrypted file?

[vedaal at nym.hush.com]

Assuming one does not use the version line in an armored gnupg encrypted message,
is there a way to tell whether the message was encrypted with gnupg 1.x or 2.x,

(Assume also that the receiver can decrypt the message.)

I tried  --list-packets  with  the highest verbose option,
but no mention of the encrypting version is listed.

TIA,

vedaal