I tried these the other day and thought they were good. They're "Improved Recipe Original Organic Free Range Chicken Stock Cubes" by Kallo; gluten and lactose-free, too- whatever that means. No Monosodium Glutamate (boo hoo!), artificial colours, flavours or preservatives.
If you can't be bothered to brew up your own chicken stock (we do this on a regular basis, and freeze it), this could be your answer. They've got an intense chicken flavour and, in my opinion, are most certainly better than the good old Knorr's version- unbelievably championed by than none other than one Marco Pierre White of infamous Wheeler's fame.
I once had dinner with a pair of sophisticated Italian sisters in Milan. They had a thing about "Mr Knorr" (along with the American Campbell's soup) which they seemed to think was the height of retrospective British cuisine. What they didn't realise is that Knorr, in fact, is a German brand, now owned by the Anglo-Dutch corporation, Unilever. And, no- I haven't got shares in Kallo, or had temptation dangled in front of me by some eager PR girl. This is a genuine recommendation.