The Caste system pre-existed the coming of the British to India. However, you could argue that they codified and made the caste system stronger as part of a divide and rule policy. The caste system was part of a European racial theory that the upper classes were morally more worthy than the lower ones. They also codified the castes and included them in the census. For instance a Brahmin of x Jati living in Punjab for instance That said, there were substantial rumblings from the British themselves who argued that to classify castes in this way was a huge simplification, which it frankly was. Further, the British were often rather incompetent through misunderstanding in trying to codify the castes. For instance they assumed that caste and race were related, which it wasn't, and created castes out of thin air where they hadn't existed before.

The effect of this was that the caste system became part of the divide and rule policy. Good jobs in the British administration were given to high ranked castes. This resulted in binding these castes which did well out of British rule to the regime and made them more reliable in combating opposition. In addition, they also divided along religious lines. Parsis for instance were enthusiastic supporters of the regime for the protection and opportunities that they brought.

You could say that the British made the caste system more crude and used it as a blunt instrument of social control