Well in this particular case,it certainly wouldn't be printed if it wasn't true and the advantage is the backing in the form of documentation.
If it proves to be true -and we have to bear in mind that long before it became, no more than, documentation- it was dialogue carried out between two people, and as one of those people is now dead, unless the other has been blackmailed, threatened, kept prisoner, paid to go abroad,suppressed the memory, had the memory chemically erased, THAT person, unless they shared it with members of emergency services, who would ALL have been required to keep it to themselves, has kept it to his/herself for 30 plus years.
We've seen pictures of feet in the newspapers. There may even have been pictures of fake June's and Sheila's....................nothing seems to be impossible when it comes to deception.