When the heads of the British intelligence agencies appear together before a parliamentary committee for the first time, they will also be on television.
There will, however, be a 2-minute delay in the broadcast, the BBC reports.
That way, if any of the three spy chiefs lets something secret slip, it can be kept from the viewing public.
Thursday's 90-minute hearing features Sir John Sawers of MI6, the external intelligence agency, Andrew Parker of MI5, the internal agency, and Sir Iain Lobban, head of the secretive Government Communication Headquarters. GCHQ, founded immediately after World War I as a code-breaking agency, has been receiving unusual and unwanted scrutiny recently because of revelations by former U.S. security contractor Edward Snowden.
Security will be tight as the three testify before the Intelligence and Security Committee.
While the Snowden leaks have raised questions in Britain about intelligence operations aimed at foreign leaders and ordinary citizens, there have been questions about the agencies for more than a decade. They reported weapons of mass destruction in Iraq that failed to materialize and then failed to predict the London transport bombings of 2005.
The ISC will also be making a case for itself Thursday, the BBC said, because of questions about its monitoring of the intelligence agencies.