1957 Boosey & Hawkes Imperial matte silver 3v compensating baritone with very clean Soundwear cordura bag that includes shoulder and detachable backpack straps.
Plays to current pitch: Stamped "L.P." near the serial #, so A = 440 (as opposed to H.P.: A = 452.5)
All slides move and pull with a pop.
Valves operate smoothly. That the horn plays the scale to pitch & slides pop-on-pull indicate that the valves are fine.