Given how simple this is, and that it is probably taught in the second or maybe even first semester of any decent applied statistics program, there is no excuse for the British study. This is not something that an even slightly competent researcher could possibly fail to notice in the data even if they somehow overlooked the information about how the definition changed ("hmm, let's look at the trend from year to year: down a bit, down a bit, same, down a bit, huge increase, down a bit, down a bit – yup, it sure looks like an upward tend to me").
Either someone was intentionally trying to mislead their audience or they were in so far over their heads – and by this I mean they knew absolutely nothing about analyzing statistics, but did so anyway – that they had no excuse for claiming their analysis was worth anything. Either way, it is important to recognize the difference between honest disagreement (which this obviously was not, since the ONS retracted it), honest mistakes (which this was not because the mistake is too glaring to make honestly), and dishonesty (either in the form of lying about the world or about one's qualifications).
This, of course, is a reference to the ONS's claim (since debunked and retracted) that women's drinking is on the rise in Britain. Go read.
