Greetings Rob.
A nice little badge you have there.
I have one the same as yours and another two, one in white metal on blades and the other blackened brass on lugs.
The white metal example, which is marginally smaller than the other two, I believe is a collar badge for the Harrow School Cadet Company.
The others,(and I include your badge in this) are, I believe either head dress badges for the same unit or were worn by The Harrow Rifles, which became part of The 5th (West Middlesex) Rifle Volunteers in 1899 and at the same time incorporated Harrow School Cadets.
As far as I am aware, the same badges were worn by both the Rifle Volunteers and the Cadets.
If I remember correctly, (which is highly doubtful
) I think there are larger examples of this badge, which unfortunately, I do not have.
At the bottom of the following link, which is slightly inaccurate, is a picture of what I believe is your badge being worn.
https://talesfromthesupplydepot.blog...fles-cap-badge
Regards.
Brian.