The location of the first accident was at a place called 'Lowton' near Warrington, Cheshire. just down the road from me. There is a monument erected for it, but is tucked away and just about viewable from a road bridge. There is a picture of the monument on a Lowton web site. Follow the link and goto photographs. http://www.lowton.co.nr/
depends whether or not you mean a commercial passenger carrying railway or a railway designed for carrying freight ie coal there were fatalities lots earlier in the tin mines of cornwall etc involving railways
cf this one (enough info here to follow up further):
" 1828. In March, locomotive number two - named Hope - blew up at Simpasture, to the north of Aycliffe, blowing its driver John Gillespie 24 yards and scalding him so badly that he died of his injuries (probably the first fatality on a publicly-owned passenger railway)."
If it's a quiz question, it just depends on how well the setter has done the research...