Thanks for this great help! One question: when you say "side" and
"base" terminals - can you clarify this a little?

Basically, in an ES fitting, there is a small point contact, which should be
live, and a large screw contact, which should be neutral. This is because it
is very easy to touch the large screw contact, so you don't want that one to
be the live one. If you get them the wrong way round, it is dangerous and an
obvious failure upon inspection.

Christian.