I have researched many British India family trees.
The India Office records at the British Library is a fantastic resource if you have British ancestors who lived in India between 1600 to 1947/8.
Tip of the day – it should be noted that if you are searching the baptism records it does not indicate who the child’s parents are. Therefore if you are searching for an ancestor with a very common surname it can be time-consuming. Try http://www.familysearch.org and see if their names appear, which would then reduce your time. Better still contact me and I can conduct the on-site research for you.
British Library family history sources include:
Returns of baptisms, marriages and burials
Wills, Administrations and Inventories
Pension Fund records
Military Service records
Civil Service records