Sinn Féin was the main target of the restrictions but they also covered 10 republican and loyalists paramilitary groups including the Irish National Liberation Army (INLA), the Ulster Volunteer force (UVF) and the Ulster Defence Association (UDA). Unlike the Irish ban, the UK version did not operate during elections and permitted the words of those subject to its controls to be spoken by actors.
I wonder how much the other groups were dubbed as well.
It seems to have been brought in after BBC staff walked out for 24 hours when government pressure led to the bosses not showing a film made about the troubles featuring Martin McGuinness and Gregory Campbell from the DUP very much speaking in their own words.
Seems to me like it was a clear attempt to try and stop media coverage of Sinn Fein and the IRA at all - but just lead to the ridiculousness of the voice overs. It obviously didn't cover the DUP and that's why Paisley's voice was heard.
This rather shows the ridiculousness of the voice ban (because it only applied when they were talking in an 'official' capacity as such) -
The use of actors' voices and certain irregularities of the restrictions were highlighted when Peter Taylor made a film about the Maze prison, featuring loyalist and republican prisoners.
The restrictions allowed Taylor to interview prisoners in their personal capacity without revoicing their contributions.
However he had to revoice the section of the film when "the IRA's spokesman for food is complaining about the size of the sausage rolls". This demonstrated the surreal nature of the restrictions.