Fernando Alonso and McLaren are back on top; the Spaniard finished more than 1.5s clear of his nearest rival Mercedes on an encouraging opening day of in-season testing for McLaren at Silverstone.
Alonso set quickest time with supersoft tyre in dry morning session before rain fell; Ocon completes most laps for Mercedes; Red Bull tested Halo 2 protection device during the morning session.
Alex Lynn enjoyed another test for Williams in third; also another young speedy Charles Leclerc impressed in his Haas F1 test ahead of the British Grand Prix and finished the morning session fourth after 17 laps in a Ferrari.
Nikita Mazepin was fifth fastest on his debut with Force India, Carlos Sainz set sixth fastest, also earned 91 laps in the Toro Rosso as the team ran a new engine cover with two ducts either side of the airbox.
GP2 competitor Santino Ferrucci, 18, set seventh fastest ahead of Mercedes and Manor driver Pascal Wehrlein, who was successively done development work on its 2017 tyres.
Rio Haryanto was ninth fastest ahead of Renault’s GP2 stars Sergey Sirotkin and Pierre Gasly.
Gasly also briefly sampled the halo cockpit protection device on his Red Bull RB12.