[1] His defeat of Frankie Neil on 17 October in London for the world bantamweight title was acclaimed as the most remarkable event in the sport in 1904.

He defeated Harry Ware in London for the British bantamweight championship on 15 December 1902, and successfully defended his title four times, beating Andrew Tokell, Bill King, Alf Fellows, and Owen Moran.

[2] On 20 March 1905, in London, Bowker knocked out Thomas "Pedlar" Palmer in the twelfth round to capture the British featherweight title.

Two months later, on 29 May, Bowker successfully defended his world bantamweight title with a 20-round decision over Pinky Evans of Yonkers, New York.

On 7 May 1910, a slimmer Bowker captured his fourth boxing title with an eighth-round knockout of Jean Audouy of France for the bantamweight championship of Europe.

A controversial loss to Digger Stanley on 17 October 1910 at the National Sporting Club cost Bowker his European and British bantamweight titles.

"[16] The end was described by author Guy Deghy: "In the eighth round of a splendidly even battle, Bowker ducked into a righthander that struck him on the jaw, and got the next one on the kidney.

At the end of his examination, the referee, Douglas, decided that there had been no foul, and Digger Stanley was awarded the first bantamweight Lonsdale Belt.

Later, he trained James O'Hanrahan who defeated Ed Tiernan in a unanimous decision at Madison Square Garden, New York, on 17 February 1925.

"O'Hanrahan gave Tiernan a boxing lesson in every round and his obvious knowledge of the game and his clean punching, especially with his right hand, reflected great credit on his trainer Joe Bowker.

In 2008, Bowker was ranked 74th on the all-time "top 100 British boxers" list, as compiled by Ron Lewis of The London Times.

[19] Bowker's bout against Jim Driscoll for the British featherweight championship is the subject of a famous painting by W. Howard Robinson, the noted representative artist and portrait painter of the early twentieth century.

The error may have originated from a book published in 1986 in which author Denis Fleming recalled a meeting with Bowker that had taken place more than a half-century earlier.

[21] It's possible that Bowker used Tommy Mahon as an alias at prizefights he didn't want the National Sporting Club to know about, as he was under contract to fight exclusively at the NSC.