CREATE TABLE table_204_476 (id DECIMAL, "name" TEXT, "date built" DECIMAL, "builder" TEXT, "works no." DECIMAL, "wheels" TEXT, "cylinders" TEXT, "notes" TEXT, "withdrawn" DECIMAL)

how long after fairfield was no. 1 built ?
SELECT (SELECT "date built" FROM table_204_476 WHERE "name" = 'no.1') - (SELECT "date built" FROM table_204_476 WHERE "name" = 'fairfield')
SELECT (SELECT "date built" FROM "table_204_476" WHERE "name" = 'no.1') - (SELECT "date built" FROM "table_204_476" WHERE "name" = 'fairfield')