What type of character is Mr. Thomas? Flat, Static, Round, Dynamic?

Mr. Thomas is a flat character in "The Destructors" by Graham Greene because he has only one or two personality traits, which are not altered in course of the narrative.
In this story that is set post-World War II, Mr. Thomas represents the older generation of Great Britain and its past tradition. His house stands alone in its neighborhood since the others have been destroyed during bombings. With its two-hundred-year-old spiraling staircase and wainscoting, this house is representative of the British upper class since it was designed by Sir Christopher Wren, the architect of the famous St. Paul's Cathedral.
When Trevor (T.) takes over as the leader of the gang, the group becomes nihilistic, finding destruction as their form of creation since they have lived around it. T. wants nothing to be left of the house; he believes the old order of Britain has failed and should be replaced. As the boys tear the house down from the interior, their act of destruction is creative because it is so cleverly done that the exterior remains standing until the lorry (truck) to which they have secretly tied the wooden struts pulls it down. When Mr. Thomas (Old Misery), who has been away on holiday, sees the end of his beautiful home he sobs. This sad, old snobbish man, in his powerlessness, now feels the terrible effects of the physical and moral destruction of war.