Forrest was appointed to Bombay Educational Department, late in 1872. He was Census Commissioner at Bombay in 1882. He was seconded to work on the Bombay Records, 1884-8, becoming Professor of English History, Elphinstone College, in 1887. He was Director, Bombay Records, in 1888, Assistant Secretary, Government of India, and Director, Government of India Records, 1894–1900.[2]
In bad health, Forrest returned to the United Kingdom in 1900.[1] He went in 1904 to Iffley Turn House just outside Oxford, was knighted in 1913, and died there on 28 January 1926.[3]
History of the Indian Mutiny (1904–1912, 3 vols.), a documentary history.[1]John Laband wrote in 1976 of historiography of the Indian rebellion of 1857 in terms of "the voluminous literature of British historians such as Kaye, Holmes and G. W. Forrest."[7]Rudrangshu Mukherjee, writing in 2008, stated that "Much of what we write and say today about 1857 is possible because of the work of [Surendra Nath Sen, Ramesh Chundra Majumdar and S B Chaudhuri] and of the great narratives produced in the second half of the 19th century and early 20th century by Charles Ball, John Kaye, G W Forrest and others."[8]
Selections from the Travels and Journals Preserved in the Bombay Secretariat (1906)[9]