An ancestor of hers, Mareen Duvall, had emigrated from France a century earlier, acquired a significant land grant in what became Prince George's County, Maryland, and established a chapel on their property which became Queen Anne Parish and ultimately St. Barnabas Church, Upper Marlboro, Maryland.

Henderson gave 4 acres (16,000 m2) of land for the use of Queen Anne's Parish called "the Glebe whereon there is a Chapple now standing.

Jonathan Boucher, an outspoken Loyalist, served as rector of Queen Anne's Parish in 1772-1776, and was driven out and sailed for England during the American War for Independence.

Edward Gantt, a clergyman and physician, who moved to the newly established national capital in Washington, D.C. Rev.

However, disestablishment of what became Episcopal Church meant repairs were deferred and the building often vacant, as Bishop Thomas Claggett noted in his visitation in 1814.

Mary Henderson's remains are still interred in a crypt beneath the church, but the marble slab which covered her grave inside the first chapel was then placed prominently in the exterior east wall of the building.

[3][6] Pursuant to a restructuring launched a decade earlier, in 1844 Henderson's Chapel became an independent congregation, Holy Trinity Episcopal Church.

The congregation's third independent rector, Reverend Dr. Harvey Stanley (1851-1885), restored the church and secured a baptismal font and other interior furnishing, which led to its rededication by Rt.Rev.

Thomas (installed in 1898), with the Porte-cochère removed and probably also the box pews and balcony formerly accessed by ladder and used by slaves before the Civil War, hence the Gothic Revival features.

The current main entrance dates from 1921, when the vestry approved removal of a southern porch and construction of a brick narthex to replace it.

Through continued expansion over the years, the school has grown steadily and now includes the Daisey Lane campus that opened in 1999.