Tall plant needed

My garden is very small, 5 yds by 9 yds but it is very full of plants.
It backs onto a path which serves our back gates.
Now the housing association who own the site have decided the paths
need upgrading (fine!) but also that for Health and Safety the lane
should have lights though we've managed for 30 years without lights!
They have put up a full height street lamp post immediately behind my
fence. We are fighting it but when/if they install the lamp it will
be 9 yds from my sitting room and bedroom windows.
I want to plant something to hide it. I had a lovely tall eucalyptus
growing there until 2 years ago but as it got tall I cut it back, as
they say you can do , but it did not regrow.
The fence runs S-N.
Any suggestions on something tall and slim?
There's not much space either width-wise or at soil level.
I don't like prunus amanaganogawa which a friend suggested.
On the new AT prog last night (more Ground Force!) someone planted
tall palms but that would not look right here.
Another euc? Or is there something else?
HELP please.

Pam in Bristol