Agent Michael Foster said Smith had been sick for some time before his death Friday, the BBC reported.
Smith first gained fame in "Not The Nine O'Clock News," which ran on BBC2 from 1979 to 1982 in the same time slot as the "Nine O'Clock News" on BBC1. The show brought Smith together with his future writing, comedy and business partner Griff Rhys Jones, and with Rowan Atkinson, an actor he would later direct in the 1997 movie "Bean."
Rhys Jones, who starred with Smith in "Alas Smith and Jones" and founded TalkBack Productions with him, said they never argued.
"He inspired love and utter loyalty and he gave it in return," Rhys Jones said. "I will look back on the days working with him as some of the funniest times that I have ever spent."
Smith, the son of a bookmaker, grew up in London and studied psychology at Oxford. He began putting on plays as a child and was active in the dramatic society during his university days.
He is survived by his wife, Pam, and one child.
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