Life of Preston, who edited the Guardian between 1975 and 1995, will be celebrated at a service in London.

A memorial service to celebrate the life of Peter Preston, former editor of the Guardian, is to be held at St Bride’s church in London’s Fleet Street.

Preston, who edited the newspaper for two decades between 1975 and 1995, died in January at the age of 79.

He joined the Guardian in 1963, aged 25. Under his editorship it became a major national force with an international reputation for agenda-setting stories, including on parliamentary sleaze.

He was responsible for introducing G2, a secondary daily features supplement, which was a revolutionary move and has since been adopted by other newspapers.

After standing down as editor he continued to work for the Guardian and Observer as a columnist. His final column on press and broadcasting was published last New Year’s Eve.

Widely regarded as one of the finest journalists of his generation, Preston, who was born in Barrow upon Soar, Leicestershire, began his career at the Liverpool Daily Post after reading English at St John’s College, Oxford, where he edited the university newspaper, Cherwell.

After joining the Guardian, he worked as a reporter, foreign correspondent, features editor and night editor before succeeding Alastair Hetherington as editor, aged 37.

Among the many tributes paid after his death, Katharine Viner, the editor-in-chief of the Guardian and Observer, described him as a “brilliant editor” and said: “His tenure was full of innovation, from launching the ground-breaking and much imitated G2 to instigating the fabulous Hillman redesign to publishing on the web unusually early, in 1994.”

Alan Rusbridger, who served as Preston’s deputy and succeeded him as editor, said: “He combined great integrity, a stubborn toughness and a decent humanity with real strategic vision.”

His son, Ben Preston, executive editor of the Sunday Times, wrote: “Dad died a good death, one that amplified the qualities we so admired while he lived. Resilience, bravery, wisdom – he was loved and loving until the end.”

Neil Kinnock, the former Labour leader, wrote: “Peter was perceptive, creative and- above all, brave in thought and deed. [He was] a newspaperman who believed that journalism in the service of the public is a cause and not just a profession, and he rigorously put that conviction into effect as Guardian editor and as an analyst and commentator.”

• The memorial service to celebrate Peter Preston’s life will be held at St Bride’s church on Thursday 5 July 2018 at 11.30am.