This is a William Cook Round Badge. It has a macassar ebony butt, handspliced onto an ash shaft.
The butt is very large - over five inches in circumference.
At the bottom of the butt, there is a semi-circular space which is now empty but would originally have held a piece of leather. This would have allowed the cue to be used as a mace.
This cue was made by Burroughes & Watts. It is a very early example, probably from the 1870s. It is the oldest cue in my collection.