Where exactly did Mr. Oxley get his information? Well, from C. G. Conn, Ltd! As early as 1921, the Conn catalog said this, "The first Sousaphone Bass ever made was built in the Conn factories more than a score of years ago" (opening line in the page below):
And just today, almost one hundred years since that catalog came out, I checked the Conn-Selmer website, and they are still making this claim! Note the very last line, which says, "Conn continued on a series of 'firsts,' building . . . the first sousaphone, built to John Philip Sousa's specifications":
It is no surprise, then, to find this claim scattered across the past one hundred years. For example, here it is in the 1926 brochure on "New Wonder Basses"; note the last paragraph:
And here it is in the 1935 Conn catalog (and the horn pictured is not even the first Conn Sousaphone!):
And here it is in a newspaper article on the Conn company from 1943:
And here it is in The Instrumentalist in 1949 where, once again, the Sousaphone featured is not even Conn's first:
And this particular Sousaphone persists as being viewed as the original. Here it is in a cute photo in the July 15, 1951 edition of the Chicago Tribune, with the date now a year earlier:
And again from that same year, this time in The Instrumentalist:
And here it is yet again, this time in the December 1959 edition of Popular Mechanics:
This particular Sousaphone, believed to be the very first one ever made, was eventually donated to the Interlochen Center for the Arts in 1970:
Here it is, two years later, being played at Interlochen by none other than Harvey Phillips!
And here's a Conn catalog page from the 1980s, making the same claim, that "Conn made the first Sousaphone." Except that he didn't!
Now, the truth is that Conn did make the first Sousaphone that Sousa kept in his band for years. In fact, Conn Sousaphones were used exclusively by Sousa from the time the first one was built, in 1898, until Sousa died in 1932.
Here is the notice of that very first Conn Sousaphone in the January 22, 1898 edition of the Music Trade Review:
But make no mistake about it. J. W. Pepper built the original Sousaphone almost three years earlier. Time to finally correct your website, Conn-Selmer!
UPDATE: August 13, 2023 - I hadn't checked in a while, but it looks like the main Conn-Selmer website no longer talks about the history of C. G. Conn, and therefore there is no mention (finally!) of "building . . . the first Sousaphone." However, the European site for Conn-Selmer still says that. We're halfway to finally eliminating this over-a-century-long false claim!
UPDATE: February 17, 2024 - I recently stumbled upon what is now the earliest reference to Conn supposedly inventing the Sousaphone. It goes way back to 1907, in the January 3 edition of the Mountain Home [Idaho] Maverick newspaper:
The column also lists the entire roster of the 1907 Maverick Home Band, so I thought I would give them their due! J. H. Garrett, "with a physique adapted to gracefully carry it" (as it says above!), was the one playing that very early C. G. Conn Sousaphone: