A recent case in the Employment Appeal Tribunal has accepted that Caste Discrimination, may (and I emphasise "may") constitute a subset of Racial Discrimination for the purposes of a Discrimination claim under the Equality Act 2010.
In Chandhok v Tirkey  UKEAT 0190_14_1912 a claim was brought by a former domestic worker against her former employers alleging that they had treated her in a demeaning and prejudiced manner. Both the worker and her employers were of Indian origin though she alleged that the reason for this treatment was her perceived lower caste status. The defendants applied to strike out that element of the claim since caste is not one of the "protected characteristics" listed in the Equality Act
The ET and the EAT refused this application in large part because it was possible that, on the facts of the case, the caste of the claimant arose from her descent in which case it could fall under the definition of race. If caste was for some other reason, ie religious, then it would not constitute race discrimination. The matter had to be decided on its own facts and therefore the "caste" element of the race discrimination claim could not be dismissed without a hearing where it could be determined whether on the facts it could fall within the protected characteristic of race/ethic origin.
The decision certainly does not throw open the doors to straightforward claims of caste discrimination but it does make such claims easier to bring which is something that caste activists have been seeking for some time. Whilst caste as a formal concept is inextricably linked to the Indian sub continent it is not unique to Hinduism. There is a great deal of evidence that both Muslims and Sikhs continue to have a strong conciousness of caste even though the concept is condemned by their own religions.
Interestingly on 31st December 2014 Parliament issued The Equality Act 2010: caste discrimination - Commons Library Standard Note which is a useful source of information on the issue including mention of the Chandhok case. I can also heartily recommend Caste discrimination: the Government’s progress which is a posting in April 2014 on the invaluable Law and Religion UK Blog