Tony Blair is expected to face questions over his links with Rupert Murdoch's media empire when he appears before the Leveson Inquiry into press standards today.
The former Prime Minister is likely to face scrutiny over whether his links with Mr Murdoch and News International became "closer than was wise", as his former lieutenant Lord Mandelson told the inquiry last week.
During his 13 years at the helm of Labour, including a decade as Prime Minister, Mr Blair sought to win over newspapers such as The Sun which had in the past savaged party leaders such as Neil Kinnock and Michael Foot.
He famously flew to Hayman Island in Australia to address News Corp executives in 1995, while last year it emerged that he had formed a close enough relationship with Mr Murdoch to have become godfather to one of the media tycoon's children in 2010.
Mr Blair's appearance comes at the start of a high-profile week for the Leveson Inquiry, with beleaguered Culture Secretary Jeremy Hunt set to give evidence on Thursday.
Mr Hunt will also face a grilling over his office's links with Mr Murdoch's News Corp, particularly during its bid to take over the satellite broadcaster BSkyB.
He will be challenged over whether his public expressions of support for the bid were compatible with the quasi-judicial role he was given by Prime Minister David Cameron.
There was unconfirmed speculation this weekend that Mr Cameron himself is due to appear two weeks later, on Thursday June 14, and that Chancellor George Osborne could yet be called to give evidence in person.
Education Secretary Michael Gove and Home Secretary Theresa May will appear on Tuesday and Justice Secretary Kenneth Clarke on Wednesday.
Also due to give evidence on Wednesday is Business Secretary Vince Cable, who was stripped of the role of deciding whether the bid could proceed last December after he was secretly recorded saying he had "declared war" on Mr Murdoch.
Mr Hunt had asked for his appearance before the inquiry to be brought forward so he could give his side of the story as soon as possible, but was rebuffed by Lord Justice Leveson.
The inquiry has been presented with a cache of emails showing that News Corp lobbyist Fred Michel received inside information about the Department for Culture, Media and Sport's handling of the bid from Mr Hunt's former special adviser Adam Smith, who quit last month after admitting he went too far in acting as a point of contact with the company.
Last week, the inquiry published a memo sent by the Culture Secretary to Mr Cameron in November 2010, weeks before he took on the quasi-judicial role, in which he appeared to be making the case for News Corp's bid to go ahead.
Mr Hunt insists that he oversaw the process "with scrupulous fairness throughout" and has received strong backing from the Prime Minister.
But Mr Cameron has also said 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.