Now that's something I didn't know... O2 customers in the UK can request to have their iPhone unlocked. At any time. Which means that affordable use while roaming is presumably now possible using a local SIM, though those tend not to give you data as well... still, I'd rather settle for phone capabilities and data via wifi than for no phone at all...

Good stuff. Have filled in the form and will see what happens... it can take a couple of weeks, apparently.