As I mentioned, area controllers are responsible for aircraft en route. They work in ATC centres, the Scottish one being near Prestwick Airport. An adjunct of area control is oceanic control, using HF radio which has longer range than VHF or UHF, and utilising procedural separation (non-radar, based on position reports and estimates, i.e. one aircraft passes a point at a given time, the next aircraft at the same level and speed cannot cross that point for 10 minutes). There are other technologies available for communication but since I don't and never have worked oceanic, I won't presume to say what they are. The eastern half of the north Atlantic is a shared resonsibility between the UK and Ireland, called Shanwick Oceanic, but in practice the controlling is done at the Scottish Centre. The western half is controlled from Gander in Newfoundland.