I recently accepted academic offer from a UK university. I comminicated wtih the head of school via phone and email, and I have not yet received the official offer letter. I am wondering how secure this situation is? In particular if this is a good time to decline other offers (I feel bad to let them wait too long and decline their offer eventually)? Or should I wait until receiving the official offer? Thank you for your input in advance.
I saw a similar question, but that is for postdoc positions and I suppose it is not exactly the same.