The show is performed by a single puppeteer inside the booth, known since Victorian times as a "professor" or "punchman", and assisted sometimes by a "bottler" who corrals the audience outside the booth, introduces the performance, and collects the money ("the bottle"). The bottler might also play accompanying music or sound effects on a drum or guitar, and engage in back chat with the puppets, sometimes repeating lines that may have been difficult for the audience to understand. In Victorian times, the drum and pan pipes were the instruments of choice. Today, the audience is also encouraged to participate, calling out to the characters on the stage to warn them of danger or clue them in to what is going on behind their backs. Also nowadays, most professors work solo, since the need for a bottler became less important when busking with the show gave way to paid engagements at private parties or public events.
The Punch and Judy show has roots in the 16th-century Italian commedia dell'arte. The figure of Punch is derived from the Neapolitan stock character of Pulcinella, which was anglicized to Punchinello. He is a manifestation of the Lord of Misrule and Trickster figures of deep-rooted mythologies. Punch's wife was originally called "Joan."
The figure who later became Mr. Punch made his first recorded appearance in England on 9 May 1662, which is traditionally reckoned as Punch's UK birthday. The diarist Samuel Pepys observed a marionette show featuring an early version of the Punch character in Covent Garden in London. It was performed by Italian puppet showman Pietro Gimonde, a.k.a. "Signor Bologna." Pepys described the event in his diary as "an Italian puppet play, that is within the rails there, which is very pretty."
In the British Punch and Judy show, Punch wears a brightly coloured jester's motley and sugarloaf hat with a tassel. He is a hunchback whose hooked nose almost meets his curved, jutting chin. He carries a stick (called a slapstick) as large as himself, which he freely uses upon most of the other characters in the show. He speaks in a distinctive squawking voice, produced by a contrivance known as a swazzle or swatchel which the professor holds in his mouth, transmitting his gleeful cackle. This gives Punch a vocal quality as though he were speaking through a kazoo. So important is Punch's signature sound that it is a matter of some controversy within Punch and Judy circles as to whether a "non-swazzled" show can be considered a true Punch and Judy Show. Other characters do not use the swazzle, so the Punchman has to switch back and forth while still holding the device in his mouth.