Yep, three years from the incident, or three years from when the damage became apparent, caused by the incident/situation.
As mentioned in previous post, for example, in cases of lung disease caused by working conditions, it's three years from when the condition is diagnosed and attributed to the working conditions.
Thanks, conny, for putting my mind at rest, I was concerned about including that bit.
I think the thalidomide cases were another example of the effect being determined after and outside of the three year limit.