Literary agent; Born January 31, 1940; Died October 20, 2008.

Pat Kavanagh, who has died of a brain tumour aged 68, was one of Britain's most respected literary agents with a stable of writers that included Robert Harris, Margaret Drabble, Ruth Rendell, Joanna Trollope, poet laureate Andrew Motion and her husband, Julian Barnes.

Kavanagh was a leader of last year's walkout by agents at the venerable Peters, Fraser and Dunlop literary agency in a dispute with its owners, CSS Stellar PLC. She had been with Peters, Fraser and Dunlop for 40 years and the rupture was a fine illustration of her no-nonsense approach to her work. The agents banded together to form United Artists and all of Kavanagh's clients went with her.

The dispute had its origins in the sale of PFD, in 2001, to CSS Stellar, a global sports and entertainment marketing group. When Kavanagh led a £4m attempt to buy back PFD, she was rebuffed, sparking her decision to set up United Agents.

Kavanagh was also, for 23 years, the agent of Martin Amis, until he switched to Andrew Wylie, an agent who has been called the Jackal, in 1995. Kavanagh's husband, Barnes, regarded the switch as a betrayal and ended his close friendship with Amis shortly afterwards.

She was born in Durban, South Africa, and met one of her future clients, Prue Leith, at the University of Cape Town. Her first career choice was to be an actress, and with the stage in mind she made her way to London in 1964. She enjoyed a brief moment on screen, in the arms of Richard Burton in the film of Dylan Thomas's Under Milk Wood.

When her acting career failed to fly she tried life as a copywriter with the J Walter Thompson agency but, ironically, she was never confident of her own writing talent. Answering an ad in the New Statesman for a literary agent, she met A D Peters and said she learned everything from him. "The great secret of negotiation," he told her, "is silence."

Many clients became personal friends but she always said that hand-holding was not part of her work and those whom she did not hold in the highest regard were quietly consigned to other partners. She would never represent someone whose work she did not admire.

She met Barnes at a party in 1978 and they married 18 months later, in the year of Barnes's debut as a bestselling novelist with Metroland. The wedding surprised many but the partnership endured, even after Kavanagh temporarily left the marital home in the early 1990s to live with the author Jeanette Winterson, author of Oranges Are Not the Only Fruit.

"She was fantastically efficient and just the person you wanted to have represent you," said Harris, a long-standing friend. "There was no-one quite like her really. And she was exotic, like a bird of paradise."

Blake Morrison, the poet and novelist, said Kavanagh was the finest agent of her generation. "She was completely trustworthy and when you sent her a typescript she would always let you know what she thought in no uncertain terms. She had complete integrity."

She and Barnes, who was six years her junior, had no children.