Ed Victor, the literary agent, has died at the age of 78.
Announcing that he had passed away, Charlie Brotherstone, of Ed Victor Limited said: "The whole of the publishing world is experiencing an incredibly sad loss at the moment."
Mr Victor, whose clients included David Cameron, Andrew Marr and Nigella Lawson, celebrated 40 years as an agent in November.
Tributes were paid to Mr Victor via twitter.
Historian Simon Schama wrote: "Ed Victor funny, stylish, gossipy, very very shrewd - those striped suits and the eyes of mischief; one of the greats of agenting."
Julia Hobsbawm added: "Ed Victor: A legend. A charming, smart, serious, glamorous, brilliant man. May he rest in peace.”
Jonny Geller, a fellow literary agent also tweeted his sorrow: "Ed Victor - a gentleman, a raconteur, a brilliant dealmaker, a lover of books. He will be missed by publishers, writers and fellow agents."
Mr Victor was born to Russian-Jewish immigrant parents who ran a photographic equipment store.
He came to Britain in 1961 on a scholarship to Cambridge University, and married his first wife, Micheline Samuels.
He began his career working on coffee-table books at the publisher, Weidenfeld and Nicholson. By 1970 he was running the department.
After a failed attempt to launch a newspaper called Ink, he went to the United States to work for publishing company Knopf.
It was in America he met his second wife, lawyer Carol Ryan.
He returned to London in 1976 to spend more time with his children and set up his own agency.
In a statement, the agency said today: "It is with the deepest sadness that we announce the death of Ed Victor CBE, Chairman and founder of the Ed Victor Literary Agency. He died of a heart attack late in the evening on 7th June at the London Clinic after a long battle with chronic lymphocytic leukaemia (CLL)."
The agency added: "Ed was a one-off: the toughest yet most professional of agents, who would always get the very best deal for his clients. An inveterate party-goer, he often attended three events in an evening. He will be a huge loss to the publishing industry and the wider world, and we miss him dearly. "
Mr Victor was awarded a CBE for services to literature in the New Year honours list in 2015.