Legend Of The Sea Devils achieved an Audience Appreciation Index score of 76.
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.
The figure is comparable with those achieved over the last series, ranging between 79 for Village of the Angels and 75 for Once, Upon Time. The most recent episode, New Year Day's Eve Of The Daleks, scored 77.