An NHS nurse who was told her marathon world record attempt was void because she wore scrubs rather than a dress has had the decision overturned following a backlash.

Guinness World Records (GWR) has awarded Jessica Anderson the title of fastest female marathon runner wearing a nurse’s uniform after admitting its requirements were outdated.

“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quite clear to Guinness World Records that our guidelines for the fastest marathon wearing a nurse’s uniform were outdated, incorrect and reflected a stereotype we do not in any way wish to perpetuate,” said Samantha Fay, the company’s vice-president.

“I want to take this opportunity to reassure everybody concerned that [GWR] is absolutely committed to ensuring we uphold the highest standards of equality and inclusiveness. We unreservedly apologise and accept full responsibility for the mishandling of Jessica Anderson’s application.”

Anderson, who has been working for the Royal London hospital’s acute admission unit for seven years, was previously told her attempt in London would not count because she wore scrubs with trousers.

GWR rules stated that a nurse’s uniform must include a white or blue dress, a pinafore apron and a traditional nurse’s cap. Anderson was told scrubs could be confused with the fancy-dress requirements for a doctor’s uniform.

The initial decision sparked widespread outrage, including among other nurses who shared pictures of themselves in uniform with the hashtag #WhatNursesWear. Anderson tweeted that she had been “blown away by the support”.

Thank you @RMayNurseDir such a lovely photo. I’m blown away by the support this has received! #whatnurseswear — Jessica Anderson (@Janderzzz) May 4, 2019

Her finish time of 3h 8m 22s from last month’s marathon has now been confirmed as a record, beating the time of 3:08.54 set by Sarah Dudgeon in 2015.

Fay said GWR would no longer accept fancy-dress outfits for the nurse’s category and instead adopt guidelines “which reflect the clothes worn by nurses in the UK and around the world”.

GWR initially told Anderson in February that she had missed the deadline for costume submissions, but announced this weekend that the situation would be reviewed after a social media backlash.

Anderson has raised more than £5,000 for Barts Health NHS trust, surpassing her original £500 target.

In an interview with Runner’s World, Anderson said: “I was quite taken aback when I read that they’d rejected my application and I did email them to ask them to reconsider but they said no.

“Some of the nurses I work with do wear dresses but mostly we wear scrubs or a tunic and trousers. I’ve certainly never seen a male nurse wearing a dress to work.”