Casual, wear jeans is okay, not too much smart.
Harrovian public school uniform
Doesn't matter at all. Just try not to look too smart or "overqualified". They try to higher people with less than average level of education because smarter people quit sooner. They told me that initially they didn't want to hire me because I have university degree and they knew I will have hard time to deal with the environment but I was very desperate, unemployed and had rent to pay. I agreed on as many hours a week as they need me for and got the job straight away.
Straw boater hat .
At the time I applied for Pret in 2016 it was in a walk in centre in Victoria station. I was wearing a Casual look when I was taken in for a interview.
Normal , no dress code