Really getting into Company history at the moment, and am a bit confused as to the relation between the British Army and the Company one. I know lots of officers served in India under what I would assume is the Company Army but also within the British Army. So was the Company Army simply a branch of the British Army that still fell under the command of Horse Guards, or was it a separate entity?
It was entirely separate from the British (not English) Army. However, the four armies cooperated in India and the Bombay Army especially was used for entirely British operations in the Indian ocean in the early Nineteenth Century. Indian Army Officers were commissioned directly by the HEIC in London and then went out to their regiment in whichever of the Presidencies they were allocated to. They would then progress through the ranks of "their" Army. British officers could transfer to a Presidency Army, usually at a superior rank to their British rank. The various Presidency armies were controlled by the Governor General at Calcutta, through the three Presidential Army headquarters in Bombay, Madras and Calcutta. A General commanding a expedition could be a King's Officer or a Company Officer, but usually, if British Army troops were involved, would be a King's Officer. A King's Officer wouldn't have direct control of Indian troops and a Company officer wouldn't have direct control of British army troops. Does that help?