The new owners immediately gave guarantees that the papers would be "signed up to no political party and free from the taint of commercial pressures".
The new board "including politicians of different views and eminent journalists, will guarantee the freedom of the editors from those pressures."
A statement from the board said the owners "today commit themselves to the preservation and growth of the titles as serious and intelligent broadsheet papers of unimpeachable integrity.
"For its part the board expects the editors to deliver honest decent, liberal-minded papers, which avoid extremism, report accurately and analyse fairly."
The board believed that "the future of a varied, free and undeferential press is essential to democracy; and that the best way to preserve that is journalistic excellence, trusted by the public."
Dr Maurice Hayes, a member of the Irish senate and a former Northern Ireland Ombudsman, has joined the board of Independent Newspapers UK, along with the former governor of Hong Kong, Chris Patten.
Dr Hayes said: "Independent Newspapers are extending their ownership of The Independent as a matter of commercial common sense, not for trophy hunting, as has been suggested, or to satisfy the whim of the proprietor.
In his view Dr O'Reilly - who is chairman of Independent Newspapers with a 27 per cent stake in the company - believes as much in hands-off proprietorship as the late Brendan Bracken, who became the last Irishman to become a London press baron when he acquired a controlling interest in the Economist and the Financial Times. On one of the few occasions when the editor of the FT felt the need to call him, Lord Bracken simply asked: "Is it about the paper?" "Yes" "You are the Editor," and the phone was put down.
"Dr O'Reilly is very much from the Brendan Bracken mould," said Brendan Hopkins, who yesterday became managing director of Independent Newspapers UK.
Andreas Whittam Smith, who founded The Independent in 1986 and will remain on the board of the company, said yesterday: "We started The Independent in order to create a newspaper which was proprietorless. If you are going to have a proprietor, Tony O'Reilly strikes me as really ideal."
Dr O'Reilly was born in Dublin in 1936 and first shot to stardom 29 rugby caps for Ireland. He then carved out an equally dazzling corporate career, notably in the dairy industry, where he spearheaded the butter brand Kerrygold.
He was soon headhunted by the American food giant HJ Heinz, rising swiftly through its ranks to become CEO and chairman, based at its Pittsburg headquarters. He used his earnings to acquire a controlling stake in Ireland's Independent Newspapers and a range of other Irish companies down the years.
His Dublin-based newspaper group has expanded steadily. It is now the largest newspaper group in Ireland as well as in South Africa, New Zealand and Portugal. It also owns the largest regional newspaper group in Australia.
Rosie Boycott, editor of the two Independent titles, said she looked forward to working with a management steeped in broadsheet experience. "Tony O'Reilly is a great, charismatic and inspirational leader, who is tremendously committed to these titles. He wants to see them restored to their former glory right at the top of the market, holding a firm and independent line."Reuse content