Year 6 and year 7 obviously because that's when I started secondary school, and year 11/12 because that's when sixth form starts.
Other than that, Year 10 and 11. 10 is the last "normal" year where you finish in July. After that your year finishes immediately after exams, except for 12 where everyone has their exams and has to come back when they are finished for a (I think) four-week period to start the next level early
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