This came just a second after Australian Mark Webber and his Red Bull team-mate defending world champion German Sebastian Vettel had gone successively fastest with laps of 2:01.325 and 2:01.200.
Dramatic climaxHamilton’s lap delivered a final stunning moment of drama at the very end of a qualifying hour packed with incident and shocks as sweeping rain produced rapidly-changing conditions.
Vettel, the series leader, wound up second ahead of Webber with Hamilton’s Mercedes team-mate German Nico Rosberg fourth.
It brought Hamilton his seventh front row start of the season on a memorable afternoon from start to finish. “It was a good job by the team,” said Hamilton, who is fourth overall 44 points in arrears of Vettel.
“So I didn’t know what was going on, but I kept pushing.
In quintessentially capricious Spa conditions, with the track drying out following a pre-session downpour, the first part of qualifying saw the Caterham and Marussia teams create a surprise after making an early switch from ‘wet’ tyres to intermediates.
This resulted in a dramatic final few minutes to Q1 that saw Alonso fastest ahead of a rejuvenated Hamilton with, remarkably, Dutchman Guido van der Garde taking third for Caterham ahead of Rosberg.