Fellowes was born in Cairo, Egypt, the youngest son of Olwen (née Stuart-Jones) and Peregrine Edward Launcelot Fellowes, a diplomat and Arabist who campaigned to have Haile Selassie restored to his throne during World War II. Fellowes was educated at Ampleforth College, Magdalene College, Cambridge and the Webber Douglas Academy of Dramatic Art.

On 28 April 1990, he married Emma Joy Kitchener, LVO (a Lady-in-Waiting to Princess Michael of Kent), the great-great-niece of the 1st Earl Kitchener, and subsequently changed his name to Kitchener-Fellowes. They have one son, Peregrine, born 1991, and bought their home in Dorset in 2002. In 2009 Fellowes was appointed a Deputy Lieutenant of the county. He is also the Lord of the Manor of Tattershall in Lincolnshire.

Fellowes is a member of Boodle's, Annabel's and Pratt's.

Television

Fellowes played the part of Kilwillie in the television series Monarch of the Glen. Other notable acting roles included the part of Claud Seabrook in the acclaimed 1996 BBC drama serial Our Friends in the North and the second Duke of Richmond in the BBC drama serial Aristocrats. In 1991, he played Neville Marsham in For the Greater Good, again for the BBC, directed by Danny Boyle. He has twice notably portrayed George IV as the Prince Regent in the 1982 television version of The Scarlet Pimpernel and the 1996 adaptation of Bernard Cornwell's novel Sharpe's Regiment. He launched a new series on BBC One in 2004, A Most Mysterious Murder, which he wrote and also introduced on screen. He is the presenter of Never Mind the Full Stops, a panel-based gameshow transmitted on BBC Four from mid-2006. He also appeared in a 1984 Swallows and Amazons television adaptation.

Film

As an actor, he has appeared in several films, including Baby with Patrick McGoohan, Damage with Jeremy Irons, Place Vendôme with Catherine Deneuve and Tomorrow Never Dies with Pierce Brosnan. As a screenwriter, he wrote the script for Gosford Park, directed by Robert Altman and won the Oscar for Best Writing, Screenplay Written Directly for the Screen in 2002. In late 2005, Fellowes made his directorial debut with the film Separate Lies, for which he won the award for Best Directorial Debut from the National Board of Review. 2009 saw the release of Young Victoria, starring Emily Blunt, for which he wrote the original script. Other screenwriting credits include Vanity Fair, The Tourist and From Time to Time, which he also directed, and which won Best Picture at the Chicago Children's Film Festival, the Youth Jury Award at the Seattle International Film Festival and Best Picture at the Fiuggi Family Festival in Rome.

Novels

His novel Snobs was published in 2004. It focused on the social nuances of the upper class and concerned the marriage of an upper-middle class girl to a peer. Snobs was a Sunday Times Best Seller and has now been published in many countries. In the 1970s he also wrote romantic novels, using the names Rebecca Greville and Alexander Morant. In 2009 he published the novel, Past Imperfect, also a Sunday Times Best Seller. It deals with the Debutante Season of 1968, comparing the world then to the world of 2008. Despite its familiar territory, Fellowes insists it is not about class but about time, and what time does to lives. It was chosen as a Richard & Judy Summer Read.

Theatre

As an actor, he appeared in several West End productions, including A Touch of Spring by Samuel Taylor, Joking Apart by Alan Aykbourn and a revival of Present Laughter by Noel Coward. As a writer, he penned the script to the current West End musical Mary Poppins, produced by Sir Cameron Mackintosh and Disney, which opened on Broadway in December 2006, and has now played all over the world.

Charity

Fellowes and his wife are committed to charity work. He is the Chairman of the RNIB appeal for Talking Books. He is a Vice President of the Weldmar Hospicecare Trust, and Patron of the South West branch of Age UK. They are both Patrons of Changing Faces, of Living Paintings, of the Rainbow Trust, and of Breast Cancer Haven, as well as supporting charities concerned with the care of Alzheimer sufferers and other causes. Fellowes is on the Appeal Council for the National Memorial Arboretum and he is also the Patron of Moviola, an initiative to facilitate rural cinema screenings in the West Country. His wife is a Patron of the Jermyn Street Theatre.