In 1887 Douglass was elected a Fellow of the Royal Society. He retired in 1892, being succeeded as Engineer-in-Chief by Thomas Matthews, and died in 1898 at his home on the Isle of Wight.
Douglass became a member of the Royal Society in 1887. He stepped down in 1892, handing over the role of Chief Engineer to Thomas Matthews, before passing away in 1898 at his home on the Isle of Wight.