The Appreciation Index or AI is a measure of how much the audience enjoyed the programme. The score, out of a hundred, is compiled by a specially selected panel of around 5,000 people who go online and rate and comment on programmes.
Doctor Who scored higher than most of Saturday's output with only Dad's Army on BBC 2 scoring higher with 89. Britain's Got Talent scored 84, with the 2013 Eurovision Song Contest scoring 69.
The score of 88 is the highest score since the season opener, Asylum of the Daleks, which scored 89.