ANSWERS

1. The Penny Black. The postal reformer was Rowland Hill.

The Penny Black was issued on 1 May 1840, but could not be used until 6 May. A few covers exist with the stamp used before the official date.

2. The Hindenburg. The reporter, Herbert Morrison, cried "Oh, the humanity!"

3. Roger Bannister, at Iffley Road, in 3 minutes 59.4 seconds

4. Queen Elizabeth II and President François Mitterrand

5. The Exposition Universelle. The tower was the Eiffel Tower.

6. Edward VII. He was succeeded by George V.

7. The Swiss Guard. New recruits are sworn in every 6 May.

8. Gordon Brown

9. Charles III and Queen Camilla

10. The Czech Republic (in Příbor, then called Freiberg, in Moravia)

11. Maximilien Robespierre

12. Robert Peary

Peary's claim to have reached the North Pole in 1909 has long been disputed, and many historians now think he fell short. That's why the question says "claimed".

13. Rudolph Valentino

14. Orson Welles, "The War of the Worlds"

15. George Clooney

16. Tony Blair

17. Gaston Leroux, "The Phantom of the Opera"

18. Henry David Thoreau

19. Alexander von Humboldt

20. Marlene Dietrich