It was "...a list of notable writers and other persons he considered to be unsuitable as possible writers for the anti-communist propaganda activities..."
"I think George was quite right to do it. ... And, of course, everybody thinks that these people were going to be shot at dawn. The only thing that was going to happen to them was that they wouldn't be asked to write for the Information Research Department."
- these were people Orwell considered Stalinist sympathisers or useful idiots essentially. Orwell of course has fought for POUM and had no truck with Stalinism. They had taken out the POUM leadership in Spain including Andreu Nin who had apparently been been beaten to a pulp by the NKVD / SIM over several days: in his book Stalinists were the enemies of Revolution.