A huge variation in food hygiene standards remains across the UK, with one in five high or medium-risk food outlets failing to meet standards, according to a study.
Which? found that the chance of a consumer buying from a food business that is not meeting hygiene standards is as high as one in three in 20 local authorities.
This figure rose to almost two in every three outlets in the lowest-rated local authority area, Hyndburn in Lancashire.
The consumer group analysed data submitted to the Food Standards Agency (FSA) and Food Standards Scotland (FSS) by 386 UK local authorities and ranked those local authority areas, focusing on those considered high risk such as hospitals, care homes and schools, and medium-risk businesses such as a local restaurant or takeaway.
It found that just 35% of Hyndburn's medium and high-risk businesses were meeting acceptable hygiene standards, while Birmingham was second on 59%.
Four London local authority areas - Newham, Ealing, Lewisham and Camden - were all ranked in the bottom 10.
In contrast, 82% of medium to high-risk businesses were compliant in Leeds, which has a comparable total of 7,603 premises.
Erewash in Derbyshire topped the table with a 97% compliance rate, and Sunderland was the highest-ranking metropolitan borough in England.
The five most-improved local authority areas since Which? last carried out its analysis two years ago are Bexley, Sunderland, Stockport, South Cambridgeshire and Barrow-in Furness.
A current review by the FSA and FSS into the food enforcement system is looking at options such as tighter checks when a food business opens and how data from businesses can be used more effectively.
But Which? said it was concerned that proposed reforms could see a potential shift towards more inspections being carried out by third parties employed by businesses in place of checks by public authorities.
Alex Neill, Which? managing director of home services, said: "People expect their food to be safe, but there is clearly still work to be done.
"As we prepare to leave the EU, the Government and regulators need to ensure that there is a robust, independent system of enforcement in place to give people confidence that the food they're eating is hygienic."
Simon Blackburn, chairman of the Local Government Association's Safer and Stronger Communities Board, said: "Although it is ultimately the responsibility of food manufacturers, suppliers and retailers to ensure the products they produce or sell comply fully with food safety law, are fit for consumption and pose no risk, councils work extremely hard to maintain and improve food safety standards.
"Despite the significant funding pressures affecting everyday services, councils are doing everything possible to maintain checks in this area, with several local authorities making significant improvements, as the report highlights. A reduction in inspections does not necessarily mean an increased safety risk.
"Forcing food outlets, including those who operate solely online, to prominently display their 'Scores on the Doors' rating - which is currently only a voluntary scheme - would not only improve consumer confidence and raise standards, but would reduce the need for and cost of enforcement action by councils."