I have a personal interest in HMS Royal Oak ( my great uncle was killed when she was torpedoed in 1939 ) I have tracked this photo down from 1925 with HMS Victory in the background in Portsmouth. Just wondering what the aircraft is !
In 1939 The Royal Oak carried a Fairey III F seaplane.
I saw an almost identical photo to the one you posted, but without the aircraft. How odd. The angle is a bit different so I guess it was taken just after...