homealone

Regarding the comments about chilled ready meals, all the food manufacturers conduct shelf life trials on these type of products. These trials attempt to simulate the 'average' conditions the product would be stored at in a domestic refrigerator.

Given that each day of extra shelf life represents a conceptual bonus to the seller, who would much rather someone bought the product, rather than them having to throw it away, it is necessarily a compromise between safety & profit - that has to err on the side of safety.

Vlad-Dracul raised a good point about storage temperatures - his fridge & freezer are operating nominally, but not everyone is as aware of the need to store chilled food below 5°C - and there can also be a significant difference in temperature between the top shelf & bottom shelf in a domestic fridge, especially large older models. This has to be taken into account when determining the shelf life - the trials conducted by the manufacturers do try to take this into account.

So while it is generally correct many products may still be 'safe' beyond the use by date, it can't be extrapolated to say that is always the case.

Another consideration is the demographic - a type of food poisoning bacteria called Listeria is capable of growth at chill temperatures (albeit more slowly the colder it gets), but elderly people, pregnant women & anyone with a compromised immune system are more susceptible to Listeria poisoning than others, so should take extra care.