Length of stay for US citizen schengen V UK
 

An American friend who is visiting Italy for three months next year hopes to have a stop over in the UK for a few days before returning to the US, she is concerned that after spending 88 days in Italy she will have to return straight home but I think as the UK is not in the Schengen area she will get a fresh stamp and the time in Italy will not count. Does anyone have knowledge or experience about where non-EU citizens in this situation stand.

You are right in your assumption. Once she leaves Italy she leaves the Shengen Area therefore there are no problems about her going to the UK. Going to the UK is the same as going to New Zealand on that respect.