The O2 thing was a fair use policy, which they were allowed to set when we were part of the EU anyway; it was almost a non story
Naturally, a number of newspapers have thus described O2’s change as the “end of free roaming” or the “return of roaming charges,” but it should be said that data usage when roaming within the EU has always tended to be treated a bit differently from texts and calls, even when the UK was still within the EU. Indeed, O2’s rivals have long had fair usage limits, particularly for UK plans that offer unlimited data or large data allowances.
For example, EE’s Pay Monthly plans already include a 50GB roaming cap when within their own Europe Zone (i.e. if you have a usage allowance of that size or bigger) and “surcharges” will apply if you go over that (here) – this equates to 36p per MegaByte. It’s a similar story for other operators’ too, with Three UK enabling you to use up to 20GB of your data allowance at no extra cost when within their Go Roam in Europe destinations.
In short, O2 are largely just adopting the same approach as their rivals, which have long had FUP caps on data for EU roaming.
However, the EE thing is not, and that is a “benefit” of the sunlit uplands