The 1886 navy reference is a red herring. It's wrong. It stems from a typo in the London Evening Standard.
The correct announcement (per the Army and Navy Gazette) was "Arthur W. Carter and Montague G. Cartwright to the Excellent, for short course of torpedo and gunnery, and then to Cambridge for gunnery". The Standard garbled this to "Arthur W. Montague J. Cartwright, to the Excellent"