The description states "Cirrus engines always seem to have been overshadowed by the more popular DH Gipsy of similar design. They had a good reputation for reliability, and the type on display powered the Avro "Avian" used by Bert Hinkler in his record-breaking England-Australia flight. Cirrus engines were originally manufactured by Cirrus Aero-Engines Limited, which was later bought by the Hermes Engines Company, which was itself bought by Blackburn Aircraft in 1934.
There was a sequence of engines bearing their names from 1925 onward. The engine on display is one of the earliest of these. Specifications (Cirrus Minor I)