The former head of the Civil Service, Gus O'Donnell, is due to appear before the Leveson Inquiry today.
One person who's bound to come up in his questionning is the Prime Minister's former communications chief, Andy Coulson - who himself appeared before the inquiry last Thursday.
The former News of the World editor resigned from his Downing Street role last year amid a row about phone hacking at the paper.
While he was at No 10, it's been revealed that he was only ever given mid-level security clearance. He was part-way through the Government's highest level security checks when he left Downing Street.
Lord O'Donnell may well be asked why he wasn't given full clearance when he first arrived and what access to secret papers he did have.
He is also likely to be questioned over whether he talked former PM Gordon Brown out of setting up a phone hacking inquiry before the last election.
Documents released show the former Cabinet Secretary thought an inquiry would be open to legal challenges and was too close to the General Election, but always insisted that the ultimate decision lay with the Prime Minister.
It will also be interesting to see if he will be drawn on Jeremy Hunt's situation. It's claimed that the Culture Secretary colluded with Rupert Murdoch's empire in a bid to prevent a public inquiry into phone hacking from being held.
At the same time the company was bidding for full control of BskyB. Jeremy Hunt denies any wrong doing and promises he will clear his name when he himself appears before Leveson.
But does Lord O'Donnell believe Mr Hunt has potentially broken the ministerial code and does he think he should be answering to the Independent Adviser on that code? We could find out later.