I apologise, as it appears the stock cubes now don't contain gluten in the UK (Europe and the US is a different matter - and we do have a lot of smaller supermarkets round here that specialise in European labelled foods, so I have seen them labelled as containing gluten recently). I've been buying a different brand for years - and still check every single time.
My suspicions about prepackaged food and ingredients is based upon sudden changes to recipes, product recalls and unpleasant reactions - for example;
'M&S recall gluten free white sourdough cob due to undeclared gluten', 'Suma organic spicy lentil soup recalled due to undeclared gluten', 'Just free gluten free recalls black pudding and white pudding due to gluten' are recalls in the last 10 months.
I don't eat out because the 'gluten free' places rarely actually prepare the food separately - a lot of chip shops will say they do it but then cook everything in the same sodding fryer, for example - and whilst some might say (and mean it) 'no gluten', the spices or seasonings could have it in and they just haven't realised/they didn't realise it meant wheat, oats, barley, yeast extract, soy, rye - or, as I am reminded by the time Gordon Ramsay said he loved putting chicken stock into vegetarians' meals, don't fucking care.
DP buys and eats gluten containing foods to eat at work so the kitchen isn't contaminated, as I was still getting caught sometimes - the reactions are fairly obvious when it's happened and sometimes, it despite eating nothing different to usual. If he gets something new, he hands the packaging to me to check first - and we've lived together for years; I'd find it very hard to trust somebody who doesn't have immediate experience without sight of packets where I can see that tiny writing for myself.