On the outbreak of the First World War, among the Admiralty's chief responsibilities was the aerial defence of Britain, as well as the more traditional role as guardian of the island's surrounding sea-ways. At that time the Royal Naval Air Service was almost wholly equipped with floatplanes of limited range and unreliable performance. The obvious need for a sea-going aircraft of long range led Captain Murray Sueter, Director of the Naval Air Department, to purchase two Curtiss flying boats.
After some operational use of these initial Curtiss flying boats, Commander John C Porte set out to improve some of the more obvious weaknesses in the design.
In September 1915, Porte was appointed in command of RNAS Felixstowe and while there finally produced his own design of flying boat. It was a large, three-engined aircraft, and was allocated the serial number 9800. Quite unofficially, it was titled the 'Porte Baby'. The largest flying boat design of its day, the 'Baby' was put into limited production, some 20 machines-and most of these saw operational service in 1916-17.
It had three Rolls-Royce Eagle engines, two installed as tractors and one as a pusher. One successfully launched a Bristol Scout from its top wing while airborne over Felixstow.