Nope, a BBC journalist or anyone not connected to the case will definitely not be privy to what is said in the recorded interview, not even a diplomat.
This is the law regarding recorded interviews:
Tape Security
Paragraph 6.2 of the Code of Practice (E) deals with the procedure to be adopted when it is necessary to gain access to the master tape. This requires a CPS representative to be present at the opening of the master tape if there are proceedings pending. A police officer has no authority to break the seal on a master copy.
It clearly states that once recorded, a random person can't just have access to what was said during the recorded interview, the only thing that's left is if someone who did the interview told this journalist, which again would mean a breach of the defendants confidentiality. Whatever way you look at it, the people conducting the interview has no business telling this journalist or a diplomat of what is said in the interview.
But he is stating a Pakistani source told him, I can only laugh at that.