I absolutely adored this episode. As a child Butlins Holiday Camp, Minehead, was my favourite holiday ever - a completely submersive experience for a whole week - entertainment from early in the morning until late at night (as a tall twelve year old, I was allowed to attend the shows in the evening but only allowed to drink lemonade) - something fresh on the hour every hour. I'm convinced Butlins was an influence on the concept of The Prisoner TV series.
Sadly, I never met a girl like Mandy or Janet at the camp.....
Link to the book:
Schoolgirls' Picture Library 003 - Secret of Sunshine Camp