CREATE TABLE table_57145 ("Number & Name" TEXT, "Description" TEXT, "Livery" TEXT, "Owner ( s ) " TEXT, "Date" FLOAT)

Which owner has a description of Mark 1 pos and is dated 1956?
SELECT "Owner(s)" FROM table_57145 WHERE "Date" = '1956' AND "Description" = 'mark 1 pos'
SELECT "Owner(s)" FROM "table_57145" WHERE "Date" = '1956' AND "Description" = 'mark 1 pos'