BBC R4 Documentary - 'Politically Charged' [The 'ABC Trial']
Presented by Clive Anderson
Produced by Jane Ashley
Broadcast December 25, 2005
Coded from tape at 128/44.1

A look at the 'ABC Trial' - the trial of two journalists, A & C,
and a former British soldier and signals intelligence, Operator B,
under Sections 1 & 2 of the Official Secrets Act (OSA). 

The trial came about after C published an article which revealed
to the public the existence and purpose of GCHQ. The first trial
opened on September 5, 1978. It stopped on September 18, 1978 when
it was discovered that one of the jurymen was a serving SAS officer!

The second trial commenced on October 3, 1978. Section 1 charges
were dropped on October 24, 1978. Defendants were found guilty under
Section 2 and received non custodial sentences, November 17, 1978.

The trial led to changes in the OSA. Public interest to know would
no longer be a defence. Nor would the fact that the 'secret' revealed
was not a secret (GCHQ, which grew out of Bletchley Park, was openly
talked about in the UK, & was certainly known to, say, the Eastern Bloc). 
http://cryptome.quintessenz.at/mirror/justice-dc.htm

.