Hi Impact,
The neon and resistor would have been across the fuse.
That might be illegal nowadays, because it uses the live side through the
load. However, it would not be illegal to use the lives of the fuses that
have not blown.
I suggest that you put neon (or other) indicators on the feed sides, then
if one goes out that would indicate a loss of supply.
That would not involve any live connections going to the load side of a
blown fuse.
You would have a row of lights, rather than one lit when a fuse blows.
There is one other arrangement that used to be used by the GPO, thats
where the fuses were wire fuses, and a small spring was pulled down using
the fuse wire, when the fuse blew, the spring returned and put a feed to
a lamp. That was low voltage only.
Hope this helps.
Regards, John