According to Colonel Oleg Gordievsky a KGB officer turned British spy, 80% of the funding for the UK Communist party and CND in the UK came from the KGB.

Gordievsky, Oleg; Andrew, Christopher (1990). KGB: The Inside Story. Hodder & Stoughton. ISBN 0-340-48561-2.

The Stasi could certainly be argued as one of the most pervasive secret services in history.

They had agents everywhere, and where agents couldn't be planted - informers were recruited, or 'inoffizielle mitarbeieter' - informal collaborators'. Members of the public recruited to be the eyes and ears of the Stasi, for a little reward every now and then.

In my region alone - bear in mind I live in the North of England, there were at least 2 suspected Stasi agents/informers in academia alone:

Robin Pearson, economics lecturer at Hull University.

Vic Allen, former professor of industrial relations at the University of Leeds.

So yes - quite common, even on an international level.

http://www.theguardian.com/uk/1999/dec/07/richardnortontaylor