I feel a bit silly writing this, but perhaps knowing about my forgetfulness might prompt others not to be so careless as I've obviously been.
I have always had a thermometer inside my refrigerator to monitor the internal temperature for chilled food, but I haven't been checking it as often as I obviously should have been - or "putting two and two together" over the past several weeks when certain foods (specially cream, for example) have been "spoiling" far more rapidly than they normally do, so I have been disposing of half-full tubs after only a very few days and buying fresh tubs. The problem is that, because it is summer (or at least what passes for summer in the north of Scotland), I have not been taking account of the fact that ambient temperatures indoors, specially at night, have been considerably higher than in much of the rest of the year.
Although my refrigerator is pretty modern (and large) and works very well, and because it is frost-free requires little maintenance whilst in use, apart from making sure the interior shelving remains clean and hygienic, specially after any inadvertent spillage or leakage, I had forgotten to adjust the rotary thermostat inside the door to regulate the temperature inside the refrigerator part to take account of the warmer weather we've been having recently; the freezer part is completely automatic and has never not done the job it is supposed to.
Yesterday I did check the inrerior thermometer properly, however, and was a little shocked to realise the refrigerator interior temperature was hovering around 12-13 degreesC, instead of the 3-5 degreesC it should be. So I have now turned up the rotary control by several steps. Overnight the refrigerator cooled down considerably, to about 0-1 degrees, so throughout today I've been making small adjustments to achieve the desired 3-5 range. I won't be making the elementary mistake of not checking the internal temperature regularly in future!
I'm now reasonably confident I won't have to throw away so much prematurely spoiled food in coming weeks as I have been finding it necessary to do recently.
NB/ It so happens the refrigerator at my home in Spain is almost exactly the same as the unit in my kitchen here in Scotland (same make and model, slightly different trim and a different body colour), but I've always been much more aware of the need to monitor/regulate the temperature there, because I expect it to be warmer, whereas for most of the year in Scotland it's less necessary, even though the central heating is on from early Autumn until late-Spring, but except in really severe winter weather I prefer not to have the central heating on all night, because I sleep better in slightly cooler air.