The Sun has a headline "Britons in Eurostar fare fury", and for once the weird hyperbole of the tabloid is pretty much spot-on.
We bought Eurostar train tickets a few weeks ago and thought they were quite expensive. It turns out that this was partly because we identified ourselves as UK residents - if we'd said we were French, German, or Australian, we would have been charged less - up to three times less.
This is not because of what we buy but simply because of our country of residence. Eurostar apparently justify this by saying that most UK-resident travellers are on business rather than leisure travel, hence are willing to pay more. So us poor idiots, who assume that being honest about our country of residence won't make our little holiday to France cost far more than it should, get ripped off as a result. Great.