It has been widely reported that Graham's absence is due to his involvement in the drinking session which led to Gareth Hock being sent home earlier in the week.
However, McNamara did not respond well to such suggestions and, after reporters continued to press him on the subject, he walked out of the meeting, which lasted just six minutes.
"There are seven very good players not playing this week," McNamara told reporters. "I'm certainly not going to talk about any individuals among those seven."
Following another question about Graham, he added: "If you're going to carry on that that questioning, we might as well stop now."
The subject briefly changed to opponents Australia, but it then switched to Hock, prompting McNamara to rise from his chair and say: "I've got to go boys anyway because the bus is going, cheers, see you tomorrow."
England match squad: Ablett, G Burgess, S Burgess, T Burgess, Burrow, Charnley, Chase, Cudjoe, Farrell, Ferres, Hall, Hill, Mossop, Roby, Sinfield (C), Tomkins, Watkins, Westwood, Widdop
Australia starting XIII: Slater, Morris, Tate, Inglis, Boyd, Thurston, Cronk, Scott, Smith (C), Tamou, Bird, Thaiday, Gallen. Replacements: Farah, Fifita, Lewis, Parker, Hayne, Myles