Jacob Milborne was born in England around 1648 and came to New York in 1668 where he was employed by the leading merchant Thomas Delavall as a clerk and bookkeeper. In the History of the State of New York, John Romeyn Brodhead writes that in an appeal heard in the Court of Assizes in 1672, the plaintiff's attorney John Sharpe was assisted by Samuel Edsall and Jacob Milborne, the latter "specially admitted to plead." Beyond this, there is no indication that Milborne either studied law or was admitted to the New York bar.
In 1690, Jacob Leisler appointed Jacob Milborne Clerk to the Council, Secretary, Attorney-General and Advocate General. In the following year, 1691, both Leisler and Milborne were hanged for treason.
Edwin R. Purple. Genealogical notes relating to Lieut.-Gov. Jacob Leisler and his family connections in New York (1877)
John Romeyn Brodhead. History of the State of New York (1871)