A KFC in West Croydon has been placed under new management after inspectors rated it just one out of five for food hygiene.
The branch in London Road was heavily criticised following its last inspection on June 26, 2014.
Its rating is the lowest score received by a branch of KFC in London according to the Food Standards Agency (FSA) website.
It was one of 152 food outlets in Croydon, including restaurants, takeaways and pubs, which received a zero, one or two rating in 2014.
The FSA says any business to have scored below a three out of five has failed the inspection.
The onus is on the eatery to organise a reinspection if they think they have made improvements.
KFC's poor score in Croydon flies against the company's usually high standard of food hygiene, with Advertiser research showing its branches scored an average of 4.53 after 131 inspections in London.
A KFC spokeswoman said: "Food hygiene and safety are top priorities for KFC and once we were alerted that the restaurant had not met our usual high standards, we took steps to rectify the issues identified and undertook a programme of upgrade and maintenance.
"The restaurant is now under new management and we are confident that when the next inspection takes place we will receive a much improved rating."
See this Friday's Advertiser for a special report on Croydon's least hygienic businesses