Regimental mufti of the Indian Army

Browsing through Sean's meticulously researched CD02 of illustrations of Gurkha uniforms (highly recommended) I was struck by the numerous examples of "regimental mufti" worn when off duty by both Gurkha riflemen and officers. That is to say the standardised almost-uniform blazers, shorts etc that served as walking out dress. This was not unique to the Gurkhas - most or all Indian regiments seem to have had their individual patterns from the nineteenth century through until 1939. Sikhs, Punjabis etc differed mainly from the Gurkhas in favouring turbans instead of round caps; and jodhpurs instead of shorts. Blazers were universal though, except during the hot weather when white kurtas (long blouses) were worn. When the Indian Mutiny broke out at Meerut in 1857 most sepoys were off duty and are described as wearing much the same form of standardised white civilian dress, indicating that the concept of regimental mufti was a very long established one. The interesting point is that British soldiers in India and at home always wore walking out uniforms - either a modified version of red full dress or whites or khaki drill. The rules in short were quite different. Did this reflect cultural differences (the British Tommy valued his right to wear a walking out uniform because, at least until 1914, it's decorative value served to "pull the birds" in modern venacular). Perhaps the Indian sepoy had different values or perhaps the Government of India saw an opportunity to save money - assuming sepoys paid for their own mufti. Does anyone know?