CREATE TABLE table_50759 ("Class" CLOB, "Wheel arrangement" CLOB, "Fleet number ( s ) " CLOB, "Manufacturer" CLOB, "Year made" CLOB, "Quantity made" CLOB, "Quantity preserved" CLOB)

What class had 1 made and fleet number of 406?
SELECT "Class" FROM table_50759 WHERE "Quantity made" = '1' AND "Fleet number(s)" = '406'
SELECT "Class" FROM "table_50759" WHERE "Fleet number(s)" = '406' AND "Quantity made" = '1'