Ian Richardson, the Scottish actor best known for his role as the scheming Francis Urquhart in House of Cards, died yesterday, aged 72.

Richardson died in his sleep at his London home in the early hours. He had been busy preparing to play a role in an episode of the Midsomer Murders television series.

Born in Edinburgh in 1934, Richardson was educated at George Heriot's School and studied later at the Royal Scottish Academy of Music and Drama in Glasgow, before going on to become one of the most esteemed actors of the stage, helping found the Royal Shakespeare Company.

However, the actor's most famous and Bafta-winning role as the Machiavellian politician in the BBC's 1990 drama not only led him to fame but coined a phrase which has entered Westminster's parlance - "You may very well say that; I couldn't possibly comment." In 2005 he said: "I have done 15 years of Shakespeare but without doubt Francis Urquhart has been the best opportunity for my reputation. The only trouble is getting rid of it - so many people seem to think that I am like him."

Richardson also portrayed the "mole" Bill Haydon in Tinker, Tailor, Soldier, Spy; Sir Godber Evans in Porterhouse Blue and Sherlock Holmes in The Hound Of The Baskervilles.

Richardson, who is survived by his wife, Maroussia, and two sons, was last seen on television at Christmas as the narrator - the Voice Of Death - in Sky One's Hogfather, and was recently seen as the Chancellor in the BBC's version of Bleak House.

His acting versatility was such that he appeared in productions on Broadway, musicals in the West End and was, perhaps oddly, familiar to viewers of American television as the man in the Rolls-Royce who asked "Pardon me, would you have any Grey Poupon?" in popular commercials for Dijon mustard. Last night Michael Dobbs, author of House of Cards, said: "I am desperately sad. He is a man I admired immensely.

"He changed my life. He made a dream of mine a reality. And he did it in a way which transfixed millions of viewers. House of Cards was Ian Richardson. He made the character and brought the whole series to life. Even John Major's leadership campaign in 1990 came to a halt at 9pm on a Sunday night so that the whole campaign team could sit down and see what was happening."

John Wallace, the principal of the RSAMD, said: "Ian Richardson was one of the finest actors to come out of any conservatoire and as one of our former students we at the RSAMD were immensely proud of his achievements.

"Ian took a great interest in the academy and our present crop of stellar students and we mourn the passing of a true patrician of the stage and one of our own."

Michael Boyd, artistic director of Royal Shakespeare Company, said: "Ian was an actor in Peter Hall's first RSC ensemble in 1960.

"Throughout the 1960's and 1970's he performed in over 23 of Shakespeare's 37 plays for the companyhis growth as an actor during his time with the company, and his commitment to that company over so many years is the embodiment of all that we are working towards now in terms of an artistic identity that is defined by ensemble.

"His son, Miles, is a member of my Histories ensemble, and will be with us for two years. We are all saddened by the loss of a friend, and a founding member of the company and our thoughts are with his family."