A British nurse who was originally denied a world record for running the fastest marathon in a nurse's uniform -- because she wore scrubs instead of a skirt -- will get her title after Guinness World Records officials backpedaled Tuesday.

Jessica Anderson, a nurse at Royal London Hospital, had finished the London Marathon in a time of 3.08:22, half a minute faster than the existing marathon record for a woman in a nurse's uniform.

But she was told by Guinness beforehand her race attire of medical scrubs with trousers didn't meet Guinness's rules for a nurse's uniform: a blue or white dress, apron, and a traditional cap.

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Officials on Tuesday reversed their decision, saying the guidelines were "outdated, incorrect and reflected a stereotype we do not in any way wish to perpetuate."

"I want to take this opportunity to reassure everybody concerned that Guinness World Records is absolutely committed to ensuring we uphold the highest standards of equality and inclusiveness," Guinness World Records Senior Vice President Samantha Fay said in a statement. "Therefore, we unreservedly apologize and accept full responsibility for the mishandling of Jessica Anderson’s application."

Officials added that they have decided to no longer allow "fancy dress clothing" for the category, and plan on updating guidelines that will "reflect the clothes worn by nurses in the UK and around the world."

Anderson, who ended up raising more than $3,000 for Barts Charity, reacted to the news in an Instagram post, saying she was "delighted" with the decision to review the criteria for the record.

"For me the issue went beyond achieving a world record," Anderson wrote. "I made a conscious decision to wear my uniform for the race, knowing that the record attempt wouldn’t be counted."

She added: "While nursing uniforms vary, one thing they have in common is that they are designed for professional women AND men who care for people in all sorts of ways across the world. I would have been doing a disservice to my profession if I had worn a fancy dress costume."

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Anderson had initially told Runner's World magazine she was "quite taken aback" when her application was rejected, and that the group's definitions were "so outdated."

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Officials from Guinness said the incident has spurred a greater review of world record marathon titles going forward.

A British nurse who ran the London Marathon in her uniform was initially denied a Guinness World Records listing because she wasn't wearing a skirt, only scrubs.

A British nurse who ran the London Marathon in her uniform was initially denied a Guinness World Records listing because she wasn't wearing a skirt, only scrubs. (Aaron Chown/PA via AP)

"The review of this category is the first review of each one of our 200+ marathon titles we will be conducting as a priority, to ensure we do not allow any costumes which bring a profession or any other subject into disrepute," Fay said. "Any we discover will be either amended to reflect modern standards, or deactivated."