For the past several weeks, the Tesco list has had "Irn Bru?" on it, as a consequence of the impending change to the ingredients. Until this week, a check of the bottles has revealed that we were still on old stock, and so I've gradually built up a supply (as each week I have bought enough for two weeks).
Yesterday, reading the bottle revealed the horrible truth that we were now on the new stuff. So that had to go back on the shelf while I completed my shop in dismay. (In the end, the story had a happy ending - it turned out that while the bottles were new, they still had cans that were in the old recipe. Score one more for the good guys!)
Which means that we've come to the crunch time. Things can go one of three ways: either the sales figures will hold up (or even improve), and the new recipe will be here to stay; or they'll drop by a reasonable amount, but not enough to force a rethink, and the new recipe will be here to stay; or sales will plummet and they'll fairly quickly have to reverse the decision (as happened with New Coke). I hate hoping for something to fail, but...
On the larger topic, I do understand why this measure has come about. The impending Sugar Tax left Barrs in a tricky spot. They had three choices: they could swallow the tax themselves, and devastate their profits; or they could pass on the tax to customers, and see a large hit in sales; or they could do what they have done.
What they couldn't do, unfortunately, is just reduce the sugar content without adding other sweeteners. The Sugar Tax is a binary thing - you pay nothing up to a threshold, and then you pay the full amount no matter how far above it you are. Irn Bru was at about double the threshold. So a reasonably reduction in sugar wouldn't be enough to avoid the tax, while cutting it by half would drastically alter the flavour (probably making it undrinkable). So, to avoid the tax, it had to be artificial sweeteners.
(They could, of course, have launched either "Irn Bru 50/50" as a new option, or introduced "Irn Bru Premium" that maintained the sugar but at a higher price. But there are problems with both options - basically, you're competing against yourself, which never ends well.)
So, that's where we are. I believe I have enough in stock to take me through to my birthday (especially since I'm still giving it up for Lent, starting on the 13th of February). By which time we'll know the outcome one way or another - either the new stuff will be here to stay, or the old recipe will be back. Or, just possibly, that "Irn Bru Premium" I mentioned may have arrived... though I'd be surprised.
#4: "The Darkling Child", by Terry Brooks