Prince Charles's letters will reveal thoughts on government
What was once private, will now — at some stage — be very public.
A future king's letters to seven government ministers — written, no doubt, in his distinctive style which includes plenty of underlinings and exclamation marks.
We have a sense of what they might contain. The former Attorney General has described them as particularly frank and he said their publication could lead the public to interpret them as disagreeing with Government policy at the time.
Those around the prince insist the contents are relatively benign and they are relaxed about their eventual publication.
Given his passion and his history of conveying blunt messages, some of Charles' letters will, at the very least, raise the odd eyebrow.
His challenge is that their release will focus attention once again on how he operates, so close to the throne.
Prince Charles divides opinion as heir.
Will he be, and can he be, a unifying monarch?