I've started this new thread as my source (The Oxford Song Book (1919) compiled by Percy C Buck, contains an extra verse.
Checking on the 'net', I find the same song in several places in exactly the same form as on the DT. @ Prof's Trad Music pages, Celtic-otter.com, & zaphod/lyrics/clares_dragoons. Unfortunately, the identical lyrics ALL include "Clare" in the last line of the first verse spelt with a numerical "1" i.e. C1are. I don't know where the words originated, but it is clear that three of the sites have merely been done with a "cut and paste", without even a cursory proof read.
The only other "early" source I find is the 'Library of Congress' which has this song on an early songsheet, undated, but put as late 1800s. This version also includes an additional verse, but not that quoted in the Oxford song book. In Both cases, the additional verse is included as verse 2, and the two choruses are applied to alternate verses.

Additional verse from Oxford Song Book

The brave old lord died near the fight,
But, for each drop he lost that night,
A Saxon cavalier shall bite
The dust before Lord Clare's Dragoons.
For never, when our spurs were set,
And never, when our sabres met,
Could we the Saxon soldiers get
To stand the shock of Clare's Dragoons.