Green’s Dictionary of Slang

(UK Und.) children used by beggars to elicit sympathy and thus money; such children are borrowed from their actual parents.

1809		Andrewes Dict. Sl. and Cant Languages n.p.: King’s Motts — female children carried on the backs of strollers and beggars, in order to claim the attention of the public, and excite their pity.
c.1830		Oriental Sporting Magazine (1873) 83: Ken-cadgers with their king’s motts, knights of the road, and also a few knights of the brush and moon, gave additional interest to the scene.
1852		Kendal Mercury 14 Feb. 3/3: The children which they carry with them are by the fraternity denominated ‘King’s motts’ [and] are borrowed for the express purpose of exciting the compassion of the public, and these children are frequently let out at so much per diem by the keepers of padding-kens.