Maybe the gun’s odd configuration, by American standards, i.e., short barrels with tight chokes, was influenced by the success, starting in the 1920s, of the Churchill XXV. (The Roman numerals signified the model's perforce 25-inch barrel length.)
It was choked tight enough, according to Chris Batha in his article below, for driven Pheasants at an average of 30 yards.
https://shootingsportsman.com/the-churchill-xxv/