alot of UK product sugar content has been lowered and replaced with flavour enhancers since the sugar tax came in a few years ago. Coke Zero is another one, its got sugar in but below the amount required to register it on the label and they boost the taste with enhancers.

The other thing is ingredients change flavour depending on the year. Tea for example is always changing slightly back and forward depending on how much rain and sun during growing, but its blended so nobody really notices except the labs importing the tea leaves.