Partner applicants have rated the interview process at Waitrose with 3 out of 5 (where 5 is the highest level of difficulty) and assessed their interview experience as 100% positive. To compare, the company-average is 82% positive. This is according to Glassdoor user ratings.
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I applied online. I interviewed at Waitrose (Birmingham, England) in Jul 2016
Interview
Online Application, then 1 interview. There is a quiz on the online application, which I believe decides whether you make it to interview or not. Rather Interesting, not too difficult.