My Mam's family come from the borders of Wicklow/Carlow. This happened in the 1930s.
My aunt Teresa was coming down the road towards her home. This is a winding country lane which crosses the Douglas River - more of a stream really - on a humpy backed bridge.
Some time previous to this a local farmer had gone missing for weeks. He was eventually found, away out in his own fields where he'd lain while the local wildlife and the elements did their job. There was no suspicion of foul play; he'd just died in the fields. He had no family so his house was left as it was when he died.
As my aunt, a young girl at the time, came down the hill towards his house, she could see a blue light in the upper window. Many people had reported seeing this light and it frightened the life out of her to see it herself. She started to hurry down the road, anxious to get past the house. As she watched, the blue light floated out of the window and she described it as bouncing along the fields. She ran like hell, making for the humpy backed bridge across the river - she had it in her head that she'd be safe if she could cross the water. As she came up to the bridge, the blue light - which had kept pace with her - flew under the bridge and away up and out over the fields where it hovered over where the man's body had been found.
It's a place of bogs and rivers so Will'o'the'Wisp is a well-known phenomenon. But Will doesn't act like this. My Granny took it so seriously that she had masses said for the man in the hope it would give him some rest.
The house is still there, happily occupied by live people now. I haven't heard any talk of blue lights in the place lately. Maybe the poor oul fella just wanted a bit of company.