The move is the first big change in the executive structure of Associated Newspapers since the deaths this summer of its owner Viscount Rothermere, and his right-hand man Sir David English.
The new Viscount Rothermere, Jonathan Harmsworth, 30, is now working closely with newly-appointed editor-in-chief Paul Dacre, and the decision on Mr Holborow's departure is seen as Mr Dacre's first attempt to make his mark under the new regime.
Mr Wright is a close friend and loyal deputy of Mr Dacre, and has worked with him for many years.
Mail on Sunday journalists were not surprised by the departure of Mr Holborow, who will take early retirement. The move had been expected since the death of Lord Rothermere, and the consequent rise of Paul Dacre. However a Mail on Sunday executive commented yesterday: "How on earth is Dacre going to explain to shareholders why he's sacked Britain's most successful editor?"
Under Mr Holborow, who edited the Mail on Sunday for six years, the paper has been an resounding success in terms of circulation.
However, there has been concern within the group that it has been too dull.
Others express surprise at how soon Mr Dacre has moved to make his mark. Attention is now focused on the fate of Max Hastings, the editor of the London Evening Standard, another paper in the Associated stable.
Fleet Street gossip has it that he might be the next to have his fate, and his record on the paper, weighed by Mr Dacre.