It stood just a few doors away from the similarly named Octagon Cellars and was one of a number of inns that sprang up off Union Street in the wake of the development of the Great Western Docks at Millbay in the late 1840s and the arrival of the railway in Plymouth (also at Millbay) in 1849.
Prior to that time, Union Street, at least the Plymouth end, had had an almost rural complexion and the impressive houses lining the street, most notably around the Octagon, had been occupied by professional men and their families. Almost overnight however that atmosphere changed, newer, smaller houses were packed in behind the street and professional ladies arrived from other ports to ply their trade.
Relatively short-lived, the Octagon Inn appears to have closed in the early 1870s when the last licensee John Leaman, who was also a cab proprietor, left and went around the corner to set up the Hansom Cab pub in Granby Street.
1857 - William Pidgen
1862 - Henry Manley
1865 - Mrs Manley
1867 - John Leaman