Overview: The last semi-final is for the four highest-scoring losers. Tonight's contenders: Stephen Burgess (leading steward. Royal Navy) on the history of the Royal Navy, 1756-1815; Mary Rattle (housewife) on the life and works of Beethoven;Frank Rogers (teacher) on 15thand 16th-century voyages of discovery; David Edwards (teacher) on the life and work of Benjamin Thompson , Count Rumford. With Magnus Magnusson from the University of Essex, Colchester.