The Willing Warlock is a character in Charmed Life.|
He gives Gwendolen Chant magic lessons in exchange for letters that were from Chrestomanci to Gwendolen and Cat's father.
The Willing Warlock is a character in Charmed Life and "Warlock at the Wheel".|
His name is never given, only the description by which he advertises his services: "warlock" (equivalent to witch) is the least powerful type of magic, and "willing" appears to be simply advertising (as well as a dodge to avoid mention his precise, unimpressive, qualifications), and probably doesn't have any technical meaning.
The story "Warlock at the Wheel" tells what happened to him afterward.|
He is a muscular young man who always needs a shave. He tends to be hired for shady jobs like making the wrong horse win at the races, or jobs that involve heavy lifting.|
The story "Warlock at the Wheel" tells what happened to him after the events of Charmed Life.
See also Charmed Life (spoilers).