I would prefer for this to not be true.
From the Guardian:
But it has now emerged that the dramatic episode may not have been purely the result of Nesbit's imagination. Another children's book – published in 1896, nine years before The Railway Children appeared – includes an episode seemingly too similar for coincidence alone.
I dunno, though. Some of the coincidences just seem like... coincidences. Like, both sets of kids receiving engraved watches? That's clearly just the proper reward in a story about trains.
But maybe I'm letting my affection cloud my judgment?