Re: Breaks it angle
Other sources claim the CIA was supplying UK with Argentine intel before and during war, and Ted Rowlands statement dates that back to at least the late '70s when he was in the Foreign Office. It's standard that they would have supplied the intel rather than the means to obtain the intel. Even with the closest possible sharing arrangement you still want to compartmentalise sources.
The other possibility is that GCHQ could already decrypt Crypto AG all by themselves, but wouldn't have revealed that to a TIVC technician and quite possibly would have continued to request intel from the CIA to conceal the ability from them too.
It seems unusual for TIVC to have given raw crypto details to GCHQ. Perhaps a result of the political and technical difficulty of achieving it any other way at such short notice, and thousands of miles away. And apparently the BND had to share it with Maximator counties because 'none of its members felt able to tackle the subject on its own'. So we have this unusually open secret known by most Western intelligence agencies and generations of junior ministers from various countries, all prone to blab for political or sexual gain. Given all that I feel a bit cheated we're only getting some of the juicy details four plus decades on :)
Biting the hand that feeds IT
