Green’s Dictionary of Slang

an agricultural labourer.

1885		Yorks. Post 4 Dec. 4/1: Poor chawbacon must cotinue to ‘chaw’ his bacon, and poor Billy Turniptop must be content to eat his red herrings.
1888		Yorks. Post 14 Dec. 5/2: Mr Lane Fox had used the expression ‘Billy Turnips-tops’ in relation to the newly enfranchised agricultural labourer.
1895		Daily Tel. 10 July in Ware (1909) 29/1: ‘Billy Turniptop’ does not seem a very respectful description of the agricultural labourer, especially during election times.
1909		J. Ware Passing Eng. of the Victorian Era.