What was the length when James Swallow had a release longer than 2.1?
CREATE TABLE "external_links" (
  "title" text,
  "series" text,
  "release" real,
  "featuring" text,
  "writer" text,
  "director" text,
  "length" text,
  "release_date" text
);
SELECT "length" FROM "external_links" WHERE "writer"='james swallow' AND "release">2.1;