Here is the extra verse that Wolfgang mentioned. The version in the DT doesn't have it:

Copied from http://wwwmcc.murdoch.edu.au/~gillard/watersons/fathom.html

FATHOM THE BOWL

Come all you bold heroes give an ear to me song.
I will sing in the praise of good brandy and rum.
There's a clear crystal fountain near England shall roll.
Give me the punch ladle. I'll fathom the bowl.

[Sung by The Watersons on The Watersons LP, and re-released on their Early Days CD.]