Della Callagher, 46, died after eating at the Railway Hotel in Hornchurch, east London in December 2012.

Chef Mehmet Kaya and Ann-Marie McSweeney were found guilty of perverting the course of justice and jailed at Snaresbrook Crown Court for 12 and 18 months respectively.

They had fabricated food safety records relating to the cooking of turkey meat.

Mitchells and Butlers (M&B), the chain which owned the pub, was fined £1.5m for placing unsafe food on the market.

The court heard that on Christmas Day 2012 the pub served lunch to 128 customers. Thirty-three of them suffered food poisoning.

But the turkeys prepared the day before were not cooled properly after cooking and not adequately reheated before being served to the guests.

Clostridium perfringens bacterium, a common cause of food poisoning, was later found in samples taken from the diners who fell ill.

The jury heard Kaya, 38, from Purfleet, Essex and McSweeney, 40, from Suttons Avenue, Hornchurch, retrospectively filled out due diligence logs before health inspectors could carry out an investigation.

Prosecutor Andrew Campbell-Tiech QC said it was “highly likely that other food-related records were fabricated.”

His Honour Judge Alastair Hammerton said the evidence revealed “systematic failings” in record keeping and that McSweeney was “in charge and in control of the cover-up.”