One of very few Loyalists to achieve any sort of national prominence in the United States after the American Revolution, Wickham may be best remembered for his role defending former Vice President Aaron Burr who was accused of treason but acquitted in 1807.

His father was a minister in the Anglican Church and remained a Loyalist as many in the colonies grew dissatisfied with the British administration and additional taxes imposed to offset the cost of the French and Indian War (which ended the year of Wickham's birth).

Following his move to Richmond, Virginia after the American Revolutionary War as discussed below, Wickham married his first cousin Mary Smith Fanning and had two children.

Despite vigorously declaring his innocence, Parker Wickham never received a trial and the legislation sentenced him to death if he returned to New York, so he lived the rest of his life in Connecticut.

After the Revolutionary War, Wickham remained in Williamsburg, Virginia and earned a degree in law from the College of William and Mary, where he became a close friend of John Marshall, later fourth Chief Justice of the U.S. After admission to the Virginia bar Wickham moved to Richmond and established a private legal practice.

His grandson Williams Carter Wickham owned a plantation in Hanover County through one such marriage and became the first descendant to serve in the Virginia General Assembly.