Green’s Dictionary of Slang

‘a dull heavy Fellow’ (B.E.).

c.1698		B.E. Dict. Canting Crew n.p.: Drumbelo a dull heavy Fellow. A meer drumbelo, a very Slug.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
c.1750–1882		B.M. Carew Life and Adventures.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
c.1850		Duncombe New and Improved Flash Dict.