The Gamekeeper usually had a cottage on a big estate and it was his job to breed and protect the game. He had to be sure there was always enough game for the lord of the castle or manor and the people who worked on the estate. He was also charged with keeping poachers away.
Today some old estates are open to shooting groups and a gamekeeper manages the operation, keeping a good amount of deer, partridge, and other game stocked on the property.
You will find names of persons appointed Gamekeeper in the Quarter Session reports, like this one from 1889...
This is from the Quarter Sessions Records Volume 8 of 1890
You may also find gamekeeper appointments in Newspapers.
Quarter Sessions Record for York, Volume 8 - 1890
Quarter Sessions Record = various (check index at back)
Game Certificates taken out in Ireland, 1854-1858; number of prosecutions for shooting game without licence
Game Certificates taken out in Ireland, 1862-1864; number of prosecutions for shooting game without licence
Gamekeeper's Directory: containing instructions for the preservation of game and prevention of poaching 1851
Game Duty Lists, Gentlemen's and Gamekeepers' Certificates, 1785-1799
Game Duty Lists, Gentlemen's and Gamekeepers' Certificates, 1800-1852
General Game Certificate, for the year 1851 - example
National Gamekeepers Association
Scottish Gamekeepers Association
Devon Gamekeeper List from newspapers 1800-1859
Devon Gamekeeper List transcribed from the North Devon Journal 1847-1859
Devon Gamekeeper List transcribed from the Western Times 1834-1860
Devon Gamekeeper List - Western Times 1848 - pdf
Finding Gamekeeper Ancestors
A day in the life of a Modern Day Gamekeeper