The torpedo armament of the British D-class submarines according to the Dutch magazine Marineblad dated 1907-1908 no.7

An item reported that the new British D-class submarines were to be armed with 3 torpedo tubes (2 bow, 1 stern).(1)

Note
1. The D-class consisting of the HMS D1-8, preceded by the C-class and succeeded by the E-class, with an armament of 3-45cm/18” torpedo tubes for which 6 torpedoes were carried and 1-7,6cm/120d quick firing gun.