An NHS nurse who was told her marathon world record attempt would only count if she completed the race wearing a skirt has seen the decision overturned after it sparked criticism on social media.
Jessica Anderson, an NHS nurse, was awarded the title after Guinness World Records (GWR) said its guidelines were "outdated" and "incorrect”.
GWR senior vice president Samantha Fay said: "Over the weekend it has become quite clear to Guinness World Records that our guidelines for the fastest marathon wearing a nurse's uniform were outdated, incorrect and reflected a stereotype we do not in any way wish to perpetuate.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.
"Therefore, we unreservedly apologise and accept full responsibility for the mishandling of Jessica Anderson's application."
Ms Anderson was told her outfit would not count as it was too close to the requirement of a doctor's uniform.
The GWR rules had stipulated that a nurse's uniform must include: a blue or white dress, a pinafore apron, and a traditional nurse's cap.
The original decision was criticised on social media, with many nurses sharing images of themselves in their uniform under the hashtag #WhatNursesWear.
Ms Fay said GWR introduced guidelines "which reflect the clothes worn by nurses in the UK and around the world".
Ms Anderson's time of 3.08:22 from the London Marathon's 26.2 mile course on April 28 has now been confirmed as the record and GWR guidelines will now be reviewed.