Hi Simon,
The first criterion to yr original query is typically the 2hr/4hr one with variations. See attachment -
4hour-2hour temp. rules.pdf 499.25KB
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My guess is that the sausages passed unless you are experiencing a tropical heatwave or they may have met some kind of unmentioned negative hygiene event. 
Assuming OK, left with the usual fridge limits. i suspect a 5 day storage time is on the unopened, labelled limit of most cooked, chilled, RTE, packaged products, and may well exceed many official opinions. The real truth may depend on ingredients. Shades of the ambient hot-dogs.
Do they sell packaged, chilled, RTE sausages in UK supermarkets? > a maximum fridge storage for an optimum input / specified preservatives etc. Plus a personal safety factor ? Not looking too encouraging unless yr fridge follows FDA rules perhaps.
Rgds / Charles.C