Conn 48B Connqueror
Date: 1941. Instrument owned by Paul Ayick.
Notice the (rimless) vocabell and the octagonal valve casing. In case you are wondering: the valves themselves are round, not octagonal. Also note that the position of the third valve slide and the tuning slide on the third valve casing are reversed from the usual/modern way. I am told the 48B was one of if not the first Conn trumpet with thick-walled brass, making it quite a bit heavier than the instruments that went before. The 48B Vocabell was produced from 1938 to 1951, has a #1½ bore (0.458"). The valves have bottom springs.
What Conn said:
Newest of the Connquerors, built to meet the demand for a wider, shorter model, easier to mute and hold. Has larger bell, giving it broader tone quality. The greatest trumpet of a great family. Gives you more power with less effort. Built in medium bore, Bb and A. patented Clickless Crysteel valves.
What Conn said in 1950:
The famous Vocabell, whose new principles of tone production are described [here], is available on the 44H Connqueror trombone and the 48B Connqueror trumpet. Both of these models are tremendously popular because of the great power available with so little effort and because of the richly brilliant tone. The trumpet is in medium bore, Bb and A. Equipped with famous Clickless Crysteel valves. These quieter, long wearing valves are patented and exclusive on Conn.