If, rather than when, British intelligence ever release decoded RSHA messages by the thousands, that will indeed be a day to savour. So far they deny being able to break the codes used.
Will that really add all that much to our knowledge? Over and above what we already know from German documents, which are still being analysed and yielding up new information.
In my opinion, Breitman was acting as a political activist rather than as an historian in his book. He was peddling the thesis that the British Government knew all about the slaughter of the Jews on the Russian Front through decrypts of German radio messages, and chose to hush it up for nefarious reasons.
In fact, the British Government did refer to German anti-Jewish actions in its propaganda, as did the Soviet Government.
Furthermore, it was British Government policy to devote its entire efforts to the military purpose of winning the war, and not allow its attention to be diverted to attempts to aid civilian populations suffering persecution at German hands.
As to the police decrypts, it comes as no surprise that they were the main source of information on the slaughter, since it was Orpo battalions acting on their own that initiated the slaughter of Jews on the Russian Front (eg Bialystok, Brest), rather than the Einsatzgruppen, which in the first few weeks were concentrating on security-related tasks, which did include summary executions of specified categories of persons, but not Jews as such.