It was an enlarged, two-seat version of the Second Monoplane that flew earlier that year.

It was a mid-wing monoplane of conventional configuration that accommodated pilot and student in tandem, open cockpits.

This prototype was displayed at the Olympia Aero Show in March 1911, and led to orders being placed for two racers to participate in the Daily Mail Circuit of Britain race.

A full-scale non-flying replica of Mercury II configuration was constructed for the Yorkshire Television series Flambards and is now displayed at the Yorkshire Air Museum.

Data from Blackburn aircraft since 1909[2]General characteristics Performance