Charles Grey (1849-1923) was born in Norfolk, England. His father was also an organist.
He taught at the London College of Music, and published quite a number of compositions, most of which are of a light nature.
"Rêverie in A-flat major" was published by Schott around 1900. It certainly fits right into the Summertime Series, but, before you dismiss it as just "another sentimental piece," did you know that most of the piece is could be considered a study in octaves?
Actually, almost every section of the piece is "in octaves." In parts, the octaves are played entirely by the right hand, while at other times, the octaves are played by both hands, meaning that each hand plays the melody, but an octave apart. The left has the tune only, but the right plays the tune and the accompaniment.
Trickier than it may sound!
In the piece you'll the characteristic Hill colors: the Viole 8' and 4' Flute of the Solo (joined together), the Solo Clarinet, played in the tenor register, then the Swell Hautboy with tremulant, now speaking smoothly and correctly.
I found this piece to be very appealing, but maybe I just like the music of Grey!
The score is attached below, as well as a photo of Charles John Grey.