This query is for a friend.

Question first: do you know of a web page widely covering the subject of
trees to create privacy in a back garden - not just a list, but basic rules,
ideas and other info on the specific subject, as well. I'd like to pass it
on.

he's erecting a new outbuilding at the bottom of his small garden - about
(wild guess) 60-70ft from back of the house. In order to build, he's
having removed an ugly conifer that's as old as the hills and as big as a
mountain, as well as being right in the way.

TYVM