George Washington was just some guy the British never heard of.
Have a listen to the History's Trainwrecks Podcast at the links or embedded players below:
De Fonblanque, Edward Barrington, 1821-1895. "Political And Military Episodes In the Latter Half of the Eighteenth Century: Derived From the Life And Correspondence of the Right Hon. John Burgoyne, General, Statesman, Dramatist". London: Macmillan and co., 1876. (around page 200 for letters to Washington)
Ellis, Joseph J. "His Excellency: George Washington". Vintage, 2005.
Marshall, John. "The Life of George Washington". Derby & Jackson, 1857.
McCullough, David, “1776” Simon & Schuster, 2006.
Wikipedia. “Thomas Gage.” 2021.