Rao Bahadur

Rai Bahadur (also Rao Bahadur in South India), abbreviated R.B., was a title of honour bestowed during British rule in India to individuals for their service to the Empire. The title was accompanied by a medal called a Title Badge. Translated, Rao means "prince", and Bahadur means "brave" or "most honourable." The equivalent title for Muslim and Parsi subjects was Khan Bahadur. For Sikhs it was Sardar Bahadur.

The people with Rai Sahib title, which was base level title were usually elevated to title of Rao Bahadur. Rao Bahadur could be elevated to level of Dewan Bahadur and so on. All these titles were, however, subordinate to the two orders of knighthood then in vogue in India – the lesser Order of the Indian Empire and the higher Order of the Star of India and a holder of a Rai Sahib Rai Bahadur or Diwan Bahadur title came lower in the order of precedence.

...
Wikipedia