Peter's Railway Holiday at Lunan Bay, Paperback/Christopher G. C. Vine

Peter is on holiday with his family in Scotland when Grandpa learns of a spectacular train crash. It happened nearby so they go exploring to find the exact spot. It's a true story where a crazy mistake led to disaster, but no-one was hurt. To show how easy it is to make a blunder like this, Grandpa tells another story which ends with a Bang!