"National Anthem of the Ancient Britons", also known as "Woad" or "The Woad Ode", is a humorous song, set to the tune of "Men of Harlech".

"Ho Jo" appears in the M. R. James' ghost story Wailing Well (1928), in which a group of masters take the Eton Scout Troop on an ill-fated camping expedition.

The song recounts the ancient British tradition of fighting naked, dyed with woad.

The song appeared in a YHA Songbook from the Youth Hostels Association in the early 1970s.

A version of the song appears in the 2009 novel Skin Overcoat by British author Skee Morif.