Story highlights A UK boy, 11, dressed as "Fifty Shades" character Christian Grey for World Book Day

Liam Scholes' school said that the costume was inappropriate and insisted it be modified

Scholes' mother told British media the costume was meant to be light-hearted

London (CNN) A British mother is standing by her decision to let her son, 11, wear a "Fifty Shades of Grey" costume to his school's World Book Day celebration.

"Fifty Shades of Grey" tells the tale of a naive college graduate's energetic trysts with a billionaire -- Christian Grey -- who has a penchant for bondage.

The Manchester Evening News reported that Liam Scholes arrived at Sale High School in northwest England dressed as Grey, complete with cable ties and an eyemask on Thursday. The school contacted Liam's mother and told her the costume was inappropriate.

Nicola Scholes told the newspaper she and her son had thought the idea was funny.

"We were walking home from school and he had the idea of going as Christian Grey," she said. "At first we laughed it off but then we discussed it with a few friends and saw the funny side and decided it was quite a good costume idea."

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