The Motor Cycle on September 28th 1916 conducted a test of Wital fuel with this gorgeous Enfield V-Twin. I have been unable to find out anything about Wital fuel. It appears to have been some sort of heavy fuel that was available at the time.
Update: a comment by David Blasco of royalenfields.com led me to find this ad,
Extreme Engineering: The mindboggling Watkins M001
17 hours ago