The combination of a sodden track and the limited number of wet and intermediate tyres permitted by the regulations meant it was only when the rain eased off in the second half of the session that drivers began work in earnest.
There was then a further delay when Bruno Senna aquaplaned into the barriers on the way out of the Becketts complex. The heavily-damaged Williams caused a 10-minute red flag period. Senna stepped out unhurt.
Sauber's Kamui Kobayashi was the initial pacesetter, as the Japanese driver showed the same flair that he had in the morning.
But his 1m56.474s was then pipped by a 1m56.345s from McLaren driver Hamilton.
The Mexican subsequently had a big spin coming out of Woodcote.
Fernando Alonso also had a late incident in the Ferrari while trying intermediate tyres, smashing the car's new-spec front wing off on the barriers as he spun across the grass.
Although times were relatively meaningless in the conditions, Heikki Kovalainen's seventh place to Caterham was certainly noteworthy.
The Finn was yet another man to go off the road, although his incident was limited to a messy trip through a big puddle in the grass.
1. Lewis Hamilton (Britain) McLaren 1:56.345
2. Kamui Kobayashi (Japan) Sauber - Ferrari 1:56.474
3. Michael Schumacher (Germany) Mercedes 1:56.545
4. Nico Rosberg (Germany) Mercedes 1:56.567
5. Sergio Perez (Mexico) Sauber - Ferrari 1:57.493
6. Jenson Button (Britain) McLaren 1:57.948
7. Heikki Kovalainen (Finland) Caterham - Renault 1:58.580
8. Kimi Raikkonen (Finland) Lotus - Renault 1:58.897
9. Nico Huelkenberg (Germany) Force India - Mercedes 1:58.943
10. Fernando Alonso (Spain) Ferrari 1:59.015
11. Paul Di Resta (Britain) Force India - Mercedes 1:59.429
12. Pastor Maldonado (Venezuela) Williams - Renault 1:59.472
13. Sebastian Vettel (Germany) RedBull - Renault 1:59.476
14. Jean-Eric Vergne (France) Toro Rosso - Ferrari 1:59.854
15. Felipe Massa (Brazil) Ferrari 2:00.565
16. Timo Glock (Germany) Marussia - Cosworth 2:00.820
17. Bruno Senna (Brazil) Williams - Renault 2:01.099
18. Vitaly Petrov (Russia) Caterham - Renault 2:01.348
19. Charles Pic (France) Marussia - Cosworth 2:03.719
20. Narain Karthikeyan (India) HRT - Cosworth 2:04.774
21. Romain Grosjean (France) Lotus - Renault
22. Daniel Ricciardo (Australia) Toro Rosso - Ferrari
23. Mark Webber (Australia) RedBull - Renault
24. Pedro de la Rosa (Spain) HRT - Cosworth