No idea what the 'official' answer is but I'd let them climb a tree with wide strong branches but no higher than my own height so I can easily lift them down if they get stuck. They'd have to have shoes with grips on too. I guess it would also depend on the 4 year old - their ability to climb and their ability to listen when you tell them to stop!
You may get inspiration from Tim Gill...he advocates risk taking and allowing children freedom rather than wrap in cotton wool I heard him speak and found him inspirational He is a consultant, researcher and author
In the current issue of Nursery World he also has an article 'How can we let go?' interesting but sorry I have not got the link to that...you may find it on NW website also lots of articles on the subject in EYE Hope it helps
Thanks for replies. I think i would allow a 4 year old to climb (i let my own children!), but risk assess along the lines of what LingDiLong said. Possibly get parental consent too. Any more views welcomed.
I am a nanny - but I allow a 4 year old to climb a tree - if it has sturdy branches, and they don't climb too high - I need to be able to carry them down if needs be However it depends on the 4 year old - are they physically able, will they listen to instruction to get down etc, will they be content with just climbing etc.