I bought a squirrel cage trap from Amazon and caught a squirrel within 10
minutes of leaving the trap open in the garden.

Once caught I quickly realised that I didn't have it in me to kill the
squirrel - as destructive as they are in chewing timber frame houses and
damaging plants and trees.

A pest control company will charge to destroy them but this incredibly
involves clubbing the poor buggers to death having placed them in a sack.
Doesn't sound right to me. A local vet will charge a consultation fee plus
other charges to humanely destroy a caught squirrel - about £60.

I've been told that you can't release them once caught. But what harm would
it do to release a squirrel in a local forest miles away from anyone where
there are already thousands - probably millions - of the critters? I'm not
saying there is no harm just asking for an understanding of what it is.