One O2 customer took it upon himself to investigate -- pretty thoroughly, we should add -- roaming performance at various Dublin locations. Not only did he discover a 3G connection was as good as it got, but also that O2 was imposing a download speed limit of around 0.5 Mbps. What's more, an O2 pay-as-you-go SIM wasn't subject to the same throttling as his contract SIM. It's worth noting that Three and a few MVNOs were also guilty of a few bum results, depending on location.

Not all roaming agreements are equal, and you might find your 4G phone can only pick up a 3G signal in some parts of Europe. Actively throttling connections is a different matter, and could be the doing of either network on the two sides of a roaming contract. In this instance, caught with its pants down, O2 has had little choice but to own up to the practice:

We've put in temporary measures to protect the service experience for customers. We're working to remove these in coming weeks. — O2 in the UK (@O2) July 25, 2017

In other words, O2 is saying its Dublin network is struggling to accommodate the uptick in roaming connections, so "temporary measures" are necessary to keep everyone online. O2 isn't the only provider having roaming issues, mind, with some Virgin Media customers reporting they're having trouble accessing data networks abroad.

Flipping the switch on free EU roaming was always going to increase the likelihood of technical hiccups, so it's almost surprising we haven't seen a flood of teething problems. Still, it's not a good look for O2, which has known for several years -- as all providers have -- that free roaming was kicking in this summer. And what's worse than secretly throttling connections and giving customers a poor level of service is being caught red-handed. Cue an Ofcom investigation and fine in three... two...

Update: O2 has issued another, similar statement: