In 1926, it was registered as G-EBJY, having been converted for use as a passenger carrier, and was loaned to Imperial Airways to supplement their commercial fleet.

Mitchell designed the aircraft in parallel with the Supermarine Scylla, as a replacement for the Royal Air Force's standard flying boat at that time, the Felixstowe F5.

[1][2] The Swan first appeared in Mitchell's planning drawings as a "Twin Engined Commercial Flying Boat", which date from July 1922.

[2] Mitchell's original plan was for an aircraft with two-bay wings of equal span which folded forwards to save storage space.

[3] Completed as a aerial reconnaissance flying boat, the Swan was first flown under its serial number N175 by Supermarine's test pilot Henri Biard on 25 March 1924.

[2] It first flew with its more powerful engine and no undercarriage on 25 June 1924; the modifications assisted in increasing its maximum speed from 92 to 105 miles per hour (148 to 169 km/h).

[4] Mitchell re-engined it with two 450 hp (340 kW) Napier Lion engines and had the landing gear removed for the tests, which took place in August 1924.

[4] For the Mark II version of the Swan, produced in February 1926, the crew were relocated to where the baggage had previously been stored, the nose was redesigned to reduce aerodynamic drag, and the wings were altered to become fixed.