One of the frustrating things about international roaming in the UK is typically your plan does not include coverage on this neutral network on the underground

Did the UK stop people from just picking up a cheap SIM at the Airport? I always like a local number when traveling. Anyway, Indian Roaming plans are so cheap these days that it's much easier and cheaper to just subscribe to them as part of the plan. These days, I don’t even need to add/activate it or anything, the providers turn it ON when I start my phone outside India and turn it off when I re-activate back in India.