The Consumer Association's Which? magazine has slammed hygiene standards at high-profile events after finding unacceptable levels of bacteria in take-away meals.
It said contamination was worst at the most prestigious events, and highest in chilled foods, which had been stored at the wrong temperature or handled by staff with dirty hands or equipment.
The investigators' list of nasties included bacillus cereus in chicken tikka and rice at the Lazeez Express stand at Twickenham stadium and listeria monocytogenes in a smoked salmon sandwich at the Cheltenham racecourse Gold Cup event in 2003.
The magazine blamed poor hygiene training for temporary staff and a likely lack of hand-washing and drying facilities.
Compass, whose All Leisure Group handles Twickenham and Cheltenham, said there had been no cases of food poisoning reported from either of the events. "All Leisure takes all issues relating to health and food safety very seriously, and on no occasion would put the health of its customers at risk," said a spokesman.