In the course of tracking down the O'Hara's, I accumulated a lot of material that it seemed churlish not to share with any interested parties. It's not as well documented as the family trees, but there is plenty of interesting material here, which I might one day get round to going something more coherent with.
There are as I suppose is to be expected the full range of the O'Hara clans who have been in India over the period of British colonisation. These include:
There are many who were not from famous families who came as privates from Ireland and went back sometimes with money, sometimes not:
Charles O'Hara who was present during the siege of Calcutta in 1760 and,
Edward O'Hara from Canada
Some such as Charles O'Hara arrived in the early 1800's amd stayed until they had done their time.
Some did a very short stint and got back to the UK very quickly, such as Samuel O'Hara.
And a few settled particularly working on he burgeoning railways at the end of the 1800's (as Anglo-Indians they had few other places to go) Patrick O'Hara.