|Sarah from Graphic with the remains of our five-way tonic test
I'm pleased to say that, after some head scratching, I did guess all five correctly. Q tonic (which, on its own, I've previously thought was distinguishable by not tasting of much at all—at great expense) emerged has actually having rather an odd taste; Sarah from Graphic put it well by saying it tasted like a mouthful of soil.
Fentiman's was the most striking: very bold flavours of lime and lemongrass. I can see why the staff think of it as a nice soft drink on its own, but too overbearing as a mixer.
Schweppes, oddly, was the one the identity of which I was most confident about—even though I would characterise it by its neutrality. Which is perhaps why it is the default tonic for many when it comes to G&T tastings.
And the two I had the most difficulty distinguishing? Fever Tree and Britvic! I can't really explain this, though in combination with gin the differences are obviously eroded. I would also expect that different gins would partner better or worse with different tonics. I would describe Fever Tree as having a mid-note complexity (where Britvic was more "scooped", emphasising high citrus notes and a bottom-end sweetness) and as I am a fan of gins like Miller's, which I think of as having a steely, high-note character, perhaps this explains my positive feelings towards it.
The results were interesting enough for us to decide to have a proper tonic test in the future. One candidate is something I wouldn't have thought to try but which Philip Wilson from Eaux de Vie recommended—Asda's own label. Watch this space.