Rape and the Raj

Rape (or alleged rape), specifically of British women by Indian men seems to loom rather large as a theme in novels about British India. The Jewel in the Crown and A Passage to India both turn on this theme. I can understand that as an idea it plays with a whole series of emotions but it seems a fairly crude literary device, given it's essential implausibility. I don't know of any comprehensive source for crime statistics of this kind but I have a really hard time believing that rape of British women by Indian men was at all common if only because opportunities would be rare and retribution savage. Anybody have access to any relevant facts?