CREATE TABLE table_23442 ("Episode" TEXT, "First broadcast" TEXT, "Rufus guest" TEXT, "Marcus guest" TEXT, "Winner" TEXT)

Who was Marcus's guest in the episode when Rufus's guest was Rory McGrath?
SELECT "Marcus guest" FROM table_23442 WHERE "Rufus guest" = 'Rory McGrath'
SELECT "Marcus guest" FROM "table_23442" WHERE "Rufus guest" = 'Rory McGrath'