John Rich, the son of the lawyer-theatre manager Christopher Rich, was baptized at St Andrew, Holborn, on 19 May 1692. Almost nothing is known of John’s childhood, and in 1714, when his father died, the lad may or may not have been prepared to take over not only a theatrical troupe but a new playhouse in Lincoln’s Inn Fields, then nearing completion. His father’s will gave him that responsibility, however, and John began his pre-destined career. First, he appeared, on 18 December 1714, costumed in mourning for his father, to speak an epilogue on the stage of the new theatre. Then, on 10 November 1715 he tried playing the Earl of Essex in "The Unhappy Favourite", his first and apparently last attempt at serious acting. He seems to have been searching for his place in the theatre world, and he finally found it in dance. He engaged a pair of French children, the Sallés, to dance in the 1716-17 season; their specialty was harlequinades, and John Rich may have danced with them in ‘A new Italian Mimic Scene between a Scaramouch, Harlequin, Country Farmer, His Wife, and others’ on 26 December 1716; by the following June the piece had been turned into a pantomime, possibly of Rich’s devising. From 1716-17 onward Rich concentrated his attention on his own dancing ability and the growing appeal of Italianate pantomimes. He called himself ‘Lun’ whenever he played Harlequin.
However, Rich and his brother Christopher Moyser Rich, who was a silent partner, almost bankrupted the Lincoln’s Inn Fields company, and they had to farm out their theatrical patent to stay in business. Ultimately Rich succeeded, becoming London’s favourite harlequin in pantomimes and entr’acte entertainments and winning audience acceptance of variety bills instead of evenings of just one play. To his credit, he understood the changing taste of London audiences and eventually forced his competition at Drury Lane Theatre to begin offering similar bills.
Thomas Davies in his "Life of David Garrick" described a typical Rich pantomime: a serious main plot and a comic subplot, similar to Renaissance Italian intermezzi between acts of straight plays: ‘By the help of gay scenes, fine habits, grand dances, appropriate music, and other decorations, he exhibited a story from Ovid’s Metamorphosis, or some other fabulous writer. Between [sic] the pauses or acts … he interwove a comic fable consisting chiefly of the courtship of Harlequin and Columbine, with a variety of surprising adventures and tricks which were produced by the magic wand of Harlequin, such as sudden transformation of palaces and temples to huts and cottages; of men and women into wheelbarrows and joint-stools …’ and the like. John Weaver, Rich’s chief rival at Drury Lane, kept to the classical story and, apparently, presented mute dance entertainments, but eventually he, too, added comic impurities, to the chagrin of sophisticated but delight of general theatregoers. One of Rich’s most popular offerings was "The Necromancer, or, Harlequin Doctor Faustus", which opened on 20 December 1723 with Rich, of course, as Harlequin. The pantomimes and other commedia dell’arte-type entertainments received so much popular attention that some critics felt Rich was not paying sufficient attention to Shakespeare and legitimate drama, but the records show that he came close to matching Garrick’s serious offerings, though with lesser talent. Garrick at Drury Lane scorned the trivial nature of pantomimes, but he eventually produced them, too.
Garrick also recognized Rich’s talent: in the prologue to his own "Harlequin’s Invasion" in December 1759 (after Rich had given up performing and his patent) Garrick said:
"When Lun appeared with matchless art and whim,
He gave the power of speech to every limb;
Tho’ mask’d and mute convey’d his quick intent,
And told in frolic gesture what he meant."
An example of one of Rich’s turns was Harlequin hatched from an egg, in "Harlequin a Sorcerer", first performed on 21 January 17