Subscribe | UPI Odd Newsletter Subscribe LONDON, Jan. 16 (UPI) -- British celebrity chef Jamie Oliver has vowed "heads will roll" after one of his restaurants used regular eggs instead of free-range eggs. The timing of the revelation was embarrassing, as it came days after a critical documentary he did about the commercial egg industry, "Jamie's Fowl Dinners," aired on national television, The Mirror reported. Advertisement Oliver is trustee of the 15 Foundation charity and founder of all four Fifteen restaurants that employ trainee chefs from disadvantaged backgrounds. Adding further to Oliver's embarrassment, it was a chicken farmer eating at the Fifteen Cornwall restaurant who recognized the so-called battery chicken eggs in the kitchen and photographed them with his cell phone, the report said. "I am speechless. We have cast iron rules on what any chef can and cannot buy in all Fifteens," Oliver told the Mirror. "I've never been so disappointed. Heads will roll."