Really nice and helpful Talent Acquisition people with an initial simple 30 min interview explaining the role and checking your CV. Moved onto 45 minute interview with someone from Process Chemistry team. Went well but I didn't have my chemistry brain on (after a trip) so I was a bit slow on the technical and didn't get invited to the on-site interview day. My bad though so I get it. I would say it's a bit harsh/unprofessional to tell you in the interview they're rejecting you rather than chucking an email later.