From Lexicanum

The Lords Dragon are a secret order consisting of an ancient as well as powerful cabal of Archmagos who exist within the ranks of the Adeptus Mechanicus. Their duties include the monitoring of the organization and insuring that it is free from both corruption as well as techno-heresy.

It is rumoured that the leaders of the Panopticon in the Lathe system of the Calixis Sector are members of the Lords Dragon.¹

Source

• ¹:Dark Heresy Inquisitors Handbook by Fantasy Flight Games (pg 136)