Who is the director when there are 2.70 million viewers?
CREATE TABLE "table1_29574579_1" (
  "episode" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "uk_viewers_million" text,
  "share_pct" text,
  "original_air_date" text
);
SELECT "directed_by" FROM "table1_29574579_1" WHERE "uk_viewers_million"='2.70';