I think everyone missed the sarcasm my comment was dripping with, British humour I guess. I'll take the downvotes.

I understand the issues with sugar, I have no arguments with it, but it is, as you say, a blunt instrument. Sadly, the opposite case; healthy food, is also too expensive for the same demographic this affects; that's a separate and independent problem though, and the evidence in OP seems to suggest the tax is (somewhat) effective, so, again, no arguments from me.

EDIT: To be clear, I'm talking about in the UK when I talk about a demographic.