The scenario (of going back in time to save someone from harm) assumes that the person travelling not only knows how to do it but knows the effects of whatever action he is planning to take, not just on the person in danger, but everybody else (including himself). Such people may well exist, but on a rather different level to the rest of us!
I am currently looking into a famous alleged timeslip case, at Rougham in Suffolk, and have found info on at least ten sightings of a vanishing house. If anyone knows anything about this case -- anything not already on the internet, that is -- I would love to hear about it.
