when I started eating Indian food in this country, "on the bone" was the norm, with a 50p surcharge for "off the bone" and a further 50p surcharge for breast rather than leg.
I can't remember the exact prices and tbh I am fairly certain, in Bradford back in the 1980's, it was probably not "Indian" (restaurants, eat in only) anymore but rather Bangladeshi or Pakistani (takeaways/delivery). I do remember the prices being as you say, more for off the bone though.
I remember my wife in the 90's getting an occasional Friday night Chicken tikka curry and peeling the meat from the bone to feed to our 1 year old, sauce and all. He loves curry btw whereas my daughter, the qualified chef, does not (She is lvl 3 Pastry Chef, so more sweet and savoury than spicy).