The Culture Secretary Jeremy Hunt is preparing to make a long-awaited appearance at the Leveson Inquiry.
As Thursday's only witness, he is likely to be asked about whether he was the right person to decide in a quasi-judicial role whether Rupert Murdoch's company News Corporation should be allowed to take over the satellite broadcaster BSkyB.
Last week the inquiry published a memo he sent to Mr Cameron in November 2010 in which he appeared to be making the case for News Corp's bid to go ahead.
Weeks later the Business Secretary Vince Cable was stripped of the quasi-judicial responsibility after he told two undercover reporters from The Daily Telegraph he was seeking to block News Corp's attempt to buy the 61 per cent of BSkyB which it did not already own, by referring the bid to regulators Ofcom.
He was secretly recorded telling the reporters that he had "declared war" on Mr Murdoch.
Mr Hunt can also expect questions about what contact he authorised between his special adviser Adam Smith and Fred Michel, News Corporation's head of public affairs in Europe.
The inquiry has previously released a cache of text messages and emails detailing a high level of contact between Mr Michel and Mr Smith.
They appeared to show News Corporation had received inside information about the Department for Culture, Media and Sport's handling of the bid from Mr Smith.
The special adviser quit last month after admitting he went too far in acting as a point of contact for the company.
Prime Minister David Cameron has given the Culture Secretary his backing but warned that if anything arises from the inquiry that suggests the ministerial code might have been breached, he will call in his independent ethics adviser Sir Alex Allan or take immediate action himself.