With access to recently-opened court files, Julie Etchingham reveals some of the Stasi's UK operations and asks why its other secrets are yet to be revealed.
Julie Etchingham
Siegfried Wittenburg
Wolfgang Welsch
Katja Hoyer
Anne McElvoy
Tom Tugendhat
Sir Graham Watson
Felix Müller
Annie Machon
Simon Cranfield-Thompson
Bernd Roth