We can find nothing to connect Reynolds with Harrow.
Site: Charles I, Hogarth, Reynolds (3 memorials)
HA1, Grove Hill, Art School
Not to be confused with Harrow School of Art. this is Harrow School's art department, hence the artists's memorials.
The two busts are on the right, east, wing of the building, which is Listed Grade II: "1896, by W C Marshall. Single-storey with 2-storey recessed wing on left and low single-storey wing on right. Simple neo-Jacobean. Red brick with stone dressings. Stone porch in angle with left wing. Central transmullioned oriel on main front under dutch gables. Wing to right has relief plaques of Hogarth and Reynolds flanking central door. High panelled chimney on left."