As vercingetorix said, it is an American idea. I read about a visit to 'New York Common IFR' by some LATCC controllers when I first joined and thought 'it could never happen here'. Then in the early 80s the 'Beeker Plan' came along (named after its authors, Dave Beech and Al Parker) and so here we are. What it failed to take account of was the dissimilar setups of ATC Operations here and in the USA; over there it was unusual to have a RAPCON (radar approach control) co located with the tower which it serves, whilst over here it was always the 'norm', so what you guys are lumbered with is a system which really was adapted to our needs rather than formulated for our needs from the word go.