Who directed the episode written by Tony O'Grady (pseudonym of brian clemens)?
CREATE TABLE "table1_2370579_1" (
  "episode_num" real,
  "prod_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "originalairdate" text,
  "filmed" text
);
SELECT "directed_by" FROM "table1_2370579_1" WHERE "written_by"='Tony O''Grady (pseudonym of Brian Clemens)';