Fry: I’m playing Mycroft in the sequel to the Sherlock Holmes film Guy Ritchie directed with Robert Downey Jr., and that sort of part is fun, but just once in a while to play a genuine all round sort of lead figure with complexity and tragedy and wit and all the sort of things that Oscar [Wilde] had was a once in a lifetime thrill.
Yeah, none of those things describe Mycroft at all. In fact he was only a few of the Arthur Conan Doyle books. A quick profile of him describes him like this...
Possessing deductive powers exceeding even those of his younger brother, Mycroft is nonetheless incapable of performing detective work similar to that of Sherlock as he is unwilling to put in the physical effort necessary to bring cases to their conclusions.
While Conan Doyle's stories leave unclear what Mycroft Holmes' exact position is in the British government, Sherlock Holmes says that "Occasionally he is the British government [...] the most indispensable man in the country." He apparently serves as a sort of human computer.
Outside of his roles in Gosford Park