Presuming a UK passport holder, Timatic says:

Visa required, except for Holders of an Overseas Citizen of India Card or Booklet, or:
Visa required, except for Holders of a Person of Indian Origin
(PIO) Card, or:
TWOV (Transit Without Visa):
Visa required, except for Holders of confirmed onward tickets for a max. transit time of 24 hours.

Transit Without Visa (TWOV): Passing through an international transit area of the airport in order to board a connecting (or to proceed by the same) flight, without entering the country (i.e. clearing immigration).

Unless stated otherwise, passengers wishing to TWOV must:
- be en-route to a third country (e.g. itinerary TYO-LON-TYO is not considered TWOV);
- prove that they will continue their journey within the prescribed period (e.g. hold onward tickets);
- have documents required for entry into the country of destination and for transit through countries en-route;
- remain in the transit area (airside) or on the aircraft.


However, I don't know what the situation would be if you missed your connection, so I'll leave it to someone who can comment on the 2hr connection time.