He passed away in a Cornish hospital on Monday after a short illness.
Warren played a key role in furthering the careers of Cilla Snowball, the AMV group chairman, and Andrew Robertson, the BBDO Worldwide chief executive, both former O&M executives.
An O&M lifer who joined the post room of the then Mather & Crowther in the 1950s, Warren rose rapidly through the ranks despite lacking much of a formal education.
Archie Pitcher, the former O&M London president, said: "His was a remarkable journey up the greasy pole. Peter had a remarkable ability to make friends with everybody he encountered."
Very much a product of the Ogilvy "old school", Warren made little secret of his disquiet at O&M’s 1989 takeover by Sir Martin Sorrell’s WPP.
Because the cultures and philosophies of O&M in its pre-WPP period and AMV were seen as so similar, and with Warren, Baulk, Robertson and Snowball having cut their teeth at O&M, AMV was dubbed "Ogilvy-in-exile".
The partnership between Warren and Baulk at O&M, where the former was chairman and the latter managing director, was broken when Baulk was poached by AMV in 1986 to serve as chief executive. Warren later joined him on AMV’s board in January 1992.
Baulk said: "I was just 33 years old and one of a number of O&M account directors when I got a phone call from Peter asking me to join his management team. That was the catalyst for everything that followed in my career.
"Peter lit up my life. He was larger than life but that was backed up by his rock-solid integrity."
Peter Mead, one of AMV’s founding partners, said: "Peter brought with him wit, wisdom and charm. Not only had he already been there and done it but was an instant success because the AMV and O&M cultures were so alike."
A bon-viveur always at his happiest with a glass of Sancerre, Warren loved to celebrate, whether it was a new business win or the promotion of one of his protégés.
Snowball said "He made creativity flourish just as much as people’s careers. He was full of life, kindness and wisdom."
On retiring from AMV in April 1999, Warren took on some non-executive assignments including five years as chairman of the Radio Advertising Bureau.
He is survived by his wife Susan, two sons and a daughter.
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