http://www.dysonmedic.com/
http://www.dysonmedic.com/DC04%20Folder/DC04%20Cable.html
shows a picture of the DC04 switch - it's difficult to tell accurately from the photograph but it appears to be a single pole switch interrupting just the live (Brown) wire - Neutral (Blue) looks like it's just connected with a simple push together Lucar type connector.
The switch will either have two connectors (one pole) or four connectors (two pole)
Peccavi
November 2009