Green’s Dictionary of Slang

bull’s wool n.1

[UK milit. bull’s wool, coarse woollen cloth or yarn]

1. [1900s–40s] second-hand, cheap or homemade clothes; also attrib.

2. [1930s–60s] (US black) stolen clothes; also attrib.

3. [20C+] (Aus.) a young man with a mop of bushy hair.