We had very old hymnals at my boarding school (in the late 1960s) and so I have not only heard but sung "Long Live the Pope." It was a favorite of mine, being so out of touch with Vatican II (the song, not me).

I can attest that when John Paul I (not II) was elected, 27 years ago, "Long Live the Pope" was played at a Catholic church in Fairfax, Virginia. The organist (a non-Catholic, as it happens) was the only person to sing it. I could have joined in, but it was all I could do to keep from laughing out loud.

To Dave's wife (not this Dave's), yes, Pius IX was pope at the time of the first Vatican Council (ca 1870), which approved the doctrine of papal infallibility. Pius was also the only Pope in office longer than John Paul II was. The only dogma officially promulgated since then that met the 'solemn magisterium' tests was that of the assumption of Mary, put forth by Pius XII in 1950.