allan tracy wrote:
Of course, this still begs the question as to why so much of the World
has railways with narrower guage than standard?

Simple, the narrower the track gauge the tighter the corners you can
have plus the less physical right of way area you have to level so it
costs less.

Surely, someone must have thought it was a good idea at the time but
why?

Brunel probably thought the same thing about standard gauge.

B2003