Ok, first of all it is PrestWICK. It's near Troon on the west coast of Scotland. It has an airport which is little used apart from a few military, cargo and Ryanair selling it as Glasgow! However, the airport has nothing to do with ATC over the Atlantic. That role is carried out from the Scottish Air Traffic Control Centre (ScATCC) which is located just outside the airport boundary and is a completely different entity.
The Atlantic control function is carried out jointly by ScATCC, Reykjavik, Santa Maria, Gander and New York depending on the tracks that the aircraft are flying. These change on a daily basis to take advantage of tailwinds. Up until last year, the tracks were fairly rigid, but satellite tracking of aircraft now allows reduced separation and hence more efficient use of the airspace. Look up ADSB and you'll see how it works.