Preston joined the Guardian in 1963 and was editor from 1975 to 1995, overseeing some of the most dramatic moments in its history

The former editor of the Guardian Peter Preston has died at the age of 79.

Preston, widely regarded as one of the finest journalists of his generation, joined the Guardian in 1963 and was editor between 1975 and 1995, overseeing some of the most dramatic moments in the newspaper’s history.

Over two decades as editor he was at the forefront of newspaper innovation, transforming the Guardian into a genuine national force with an international reputation, and instigating a radical and much admired redesign that helped the newspaper fight back against the launch of the Independent and a brutal price war.

Preston also came up with the concept, now commonplace but at the time revolutionary, of a secondary daily features supplement with the launch of G2.

He continued to work for the Guardian and Observer as a columnist after standing down as editor. Preston’s final column on press and broadcasting was published on New Year’s Eve.

Katharine Viner, the editor-in-chief of the Guardian and Observer, said Preston was a “brilliant editor” of the newspaper as well as a “generous and supportive ex-editor”.

She said: “His tenure was full of innovation, from launching the groundbreaking and much-imitated G2 to instigating the fabulous Hillman redesign to publishing on the web unusually early, in 1994.

“Since I became editor-in-chief of the Guardian and the Observer in 2015, Peter has been a kind and unobtrusively supportive friend, providing advice and insights and the kind of ballast that could only come from someone who’d been there and done it.

“His last email to me was to praise the Guardian’s membership figures and ended with the comment ‘hope you’re in good heart’. He will be missed by everyone at the Guardian.”

Alan Rusbridger, who served as Preston’s deputy and succeeded him as editor in 1995, said the Guardian owed him an immense debt.

“Peter embodied all the best virtues of the paper he edited with such distinction for so long,” Rusbridger said. “He combined great integrity, a stubborn toughness and a decent humanity with real strategic vision. The paper owes him an immense debt.

“Peter preferred to be an outsider. He was not one to join clubs. He didn’t seek the company of politicians. He was gritty, dogged – and brave. He led from the front.

“He was also a great innovator. Peter transformed the idea of features journalism in the Guardian. His dramatic remaking of the paper in 1988 was as bold a stroke of radical design as anyone had seen. He was always curious and impatient to know ‘what next?’

“Finally, he was a great internationalist. To the end he worked tirelessly for the protection of reporters and editors around the world and towards the education of journalists in Eastern Europe and Africa. He will be sorely missed.”

John Mulholland, editor of the Observer, said Preston had been a “loyal friend” to the newspaper as well as its media columnist for more than 20 years.

“He was a frequent visitor to our offices and invariably offered wise counsel, often laced with a mischievous sense of humour,” he said. “He was a delight to spend time with. We greatly valued his writing, his enormous warmth, and his unmatched journalistic judgement.”

One of Preston’s first acts as editor of the Guardian was to help move the newspaper into modern London offices in Farringdon Road in 1976, which included moving its printing floor in less than 48 hours. This relocation provided a new base from which Preston and the Guardian were able to cover the increasingly polarised political climate of the late 1970s and early 1980s.

A radical redesign of the Guardian in 1988 ensured the newspaper enjoyed a new period of success despite the launch of the Independent in 1986 and a price war among broadsheets instigated by the Times. The circulation of the Guardian hit record levels under Preston, at one stage clearing 500,000 copies a day.

Michael White, former political editor of the Guardian and who worked with Preston, said: “At first glance Peter Preston was an improbable Fleet Street editor. He wasn’t charismatic and never raised his voice, he was taciturn and soft-spoken, often elliptical, both in conversation and his writing. He chewed the ends of biros.

“But beneath the outward diffidence lay a powerful determination and nimble intelligence which he deployed constantly to refresh the Guardian through two tough decades, Quick and clever, with a warm, mischievous sense of humour, Peter loved print and never lost faith in the future of newspapers.”

The success of the Guardian under Preston was underpinned by agenda-setting stories, some of which led to the Conservative government under John Major becoming engulfed by sleaze scandals.

The Guardian sparked the cash-for-questions affair in 1994 when it alleged that then-MPs Neil Hamilton and Tim Smith had been paid to ask questions on behalf of Mohamed Al-Fayed. Hamilton launch a libel action against the Guardian but eventually dropped his cases in a major victory for the newspaper.

One incident that occurred during his editorship that Preston expressed regrets over was the jailing of Sarah Tisdall, a Foreign Office clerk, in 1983.

Tisdall was jailed for leaking details to the Guardian about the movement of cruise missiles. The newspaper initially won a legal battle against the government about revealing its source but when the decision was overturned the Guardian handed over the relevant documents.

Preston was born in 1938 in Leicestershire. His father died from polio when Preston was a child and then he caught the disease too. He survived and went on to win a place at the University of Oxford, where he edited the Cherwell, the student newspaper.

After graduating, Preston joined the Liverpool Daily Post as a trainee before being hired by the Manchester Guardian in 1963 at the age of 25.

Preston started as the newspaper was undergoing its transformative move from Manchester to London, with editor Alastair Hetherington moving to the capital in 1964.

Preston worked as a reporter, foreign correspondent, features editor and night editor. He became editor in 1975 at the age of just 37 after Hetherington announced he would stand down. Preston was chosen over his friend John Cole by a committee set up by the Scott Trust, which owns the Guardian. Preston and Cole remained friends until Cole died in 2013.

Alongside his successful career as a journalist, Preston wrote two novels, Bess and 51st State.