A meat distribution company supplying elite hotels and government offices in London transported meat in rancid conditions, the BBC has learned.
Experts said there was a risk of potentially fatal food poisoning
The allegations of potentially fatal breaches of health, safety and hygiene laws against McLaren Foods, of Ashford, Kent, date back more than two years.
However, no action can be taken as the business has gone into administration.
Former employee Alan Castell said often rotten meat would be transported in vans which were not disinfected after.
McLaren, which had satellite depots around the country up until March this year, also supplied top schools and hospitals.
Van driver Mr Castell said: "In the back of the van it was quite often rotten meat, even once you'd turned the fridge up to sort of chill the van out which would reduce the smell and stuff.
"Every time you opened the door it would hit you straight away."
He said the vans were disinfected "certainly not on a daily, some not even on a weekly basis at all".
"But it did get worse because sometimes when deliveries weren't done, that would be taken home and then that delivery would then be delivered the following day even though it had been sat in the back of a van outside a driver's driveway," he added.
Mr Castell said the meat would not have been refrigerated because the engine would have had to have been kept running.
But it was still delivered the next day, he added.
Former staff transported raw and cooked meat together with blood dripping from bags of raw meat contaminating the shelves below.
Experts told the BBC such a practice was a recipe for food poisoning and was potentially fatal given that deliveries were made to care homes and hospitals.
Mr Castell's delivery route was in the West End of London, and included the Treasury, the Foreign and Commonwealth Office, hospitals, schools - including Westminster, St Paul's and the London Oratory - and staff restaurants at hotels including the Dorchester and Claridges.
He filmed short video clips and took photos on his mobile phone.
His evidence is backed by the company's own internal inspection reports and minutes of meetings for both 2005 and 2006.
Mr Castell contacted his local environmental health office in Chelmsford, Essex, which conducted an inspection, giving prior notice.
Officials said a spot check would have been over zealous and against the government's desire for local authorities not to be heavy handed.
Environmental Health officers deemed conditions at the Chelmsford depot to be satisfactory although it closed down shortly after the inspection due to financial difficulties.
Food Standards Agency special advisor Professor Paul Hunter, of the University of East Anglia, said the situation highlighted problems across the food industry.
He said: "My impression is that this is probably at the worst end of the spectrum but I would be very surprised if this was also the only example around the country."
The BBC tried to contact McLaren's former operations director and managing director but neither wanted to comment.
Mr Castell had been taking a case of unfair dismissal, under whistle-blowing legislation, to an employment tribunal.
However, once the company went into administration there was no point because had he won he would have simply joined a list of creditors.