Historians often rate the ICS, together with the railway system, the legal system, and the Indian Army, as among the most important legacies of British rule in India. この文面から見るとBritish India ArmyはICSとは別組織との解釈が捉えますね。そしてBIAを調べると、陸軍とも別の組織→

英語wikiの方で「Historians often rate the ICS, together with the railway system, the legal system, and the Indian Army, as among the most important legacies of British rule in India.」とIndian armyと併記されているようです Wikipediaがどこまで正確かは分かりませんが…😅