Mugello winner Pedrosa was third fastest halfway through session, but slipped back to sixth by the flag, with Marco Melandri
(Gresini Honda) seventh, Aleix Espargaro (Pramac Ducati eighth, Marco Simoncelli (Gresini Honda) ninth and Nicky Hayden
(Ducati Marlboro) tenth.
Slower to adapt to the circuit were veterans Colin Edwards
(Tech 3 Yamaha) and Loris Capirossi
(Rizla Suzuki), who were left just twelfth and 15th. Mika Kallio, who has been battling a shoulder injury since Le Mans, was 16th and last, just over four seconds from Lorenzo.
Computer simulations had suggested that the wide and flowing Silverstone layout could become the fastest circuit on the present calendar, but lap times on Friday weren't as fast as expected.
The quickest circuit is presently Phillip Island in Australia, where Casey Stoner
set an official 'best lap' at an average speed of 180.598km/h on his Ducati in 2008.
The official race lap record for Phillip Island is an average of 177.803km/h by Nicky Hayden, on a Honda, in the same year.
Lorenzo's average speed at Silverstone on Friday was 168.640km/h, still more than enough to test the 800cc motorcycles to their limits, and lap times are likely to drop further... providing the rain doesn't return.
The highest top speed on Friday was 310.79km/h by Pedrosa, whose factory RCV team-mate Dovizioso set a 309.54km/h to be next best.
4. de Puniet