SSD,
Thanks for posting the Winchfield accident report. I hadn't heard of it before.
Who would have thought that a castellated nut and split pin was less safe than a plain nut and split pin! They were VERY lucky that the third rail was on that side of the loco. "Tangmere" doing a pole-vault on the connecting rod doesn't bear thinking about.
I'm reminded of the proverb about kingdoms and horse-shoe nails.