Mycroft Holmes or Richard Epstein?

The following passage is from Arthur Conan Doyle's The Adventure of the Bruce-Partington Plans :

The conclusions of every department are passed to him, and he is the central exchange, the clearinghouse, which makes out the balance. All other men are specialists, but his specialism is omniscience.

Is it describing Mycroft Holmes' (Sherlock's older, even smarter brother) or Richard Epstein?

     or     ?