A tidy 1923 patent step jaw spanner by FASTNUT of London.

Marked '"FASTNUT" REG PAT NO.194041' in the recessed section on one side with 'NO.1 WORLDS CHAMPION' on the other.

The stepped jaws were designed to fit three different sizes in each jaw and also provide a ratchet type action from an open ended spanner. 

A few surface pitting and staining spots but otherwise a nice example.

Approximately 6³/₄ inches overall length.