AOG - you asked "I wonder what the exam pass rate is in English? "
It's a primary school so you must mean SATS scores. The latest I could find without a major search was for 2014.
In 2014, 79% of pupils attained Level 4 or above in the key stage 2 grammar, punctuation and spelling test. This is an increase of four percentage points since 2013.
In 2014, the school's result was in the top 40% of similar schools' results, and in the middle 20% of all schools.
http://dashboard.ofsted.gov.uk/dash.php?urn=131750
As for the use of interpreters at parents' evenings I agree fully with Mamyalynne. The school has to try to make the best of the intake it gets- and it seems to be doing a good job in challenging circumstances.