Valtteri Bottas topped a very quiet hour of practice at the British Grand Prix in which only 10 drivers set a lap time.

Heavy rain doused the middle sector of the Silverstone circuit just as the hour-long session started, leaving the track unsuitable for either intermediates or slicks. The entire field nonetheless embarked on at least one installation lap on intermediate rubber, but most did no more than another lap or two before returning to their garages.

Hamilton was the lone exception, rejoining the circuit with 10 minutes remaining to entertain the crowd, clocking up a session-high 10 laps and some very limited aero data for Mercedes’s new upgrade package.

It was enough running to just about dry that problematic middle sector enough for slicks, and with four minutes left he and most of the rest of the field switched to slicks on an attempt to salvage something from the session. Lance Stroll, however, suffered a snap of oversteer traveling through the damp Copse and beached himself in the gravel, triggering a red flag before most drivers had managed to set a time.

Alfa Romeo’s Bottas emerged from the hour with the quickest time half a second ahead of old Mercedes teammate Hamilton, with Ferrari teammates Carlos Sainz and Charles Leclerc following an unrepresentative 0.7s and 1.5s off the pace.

Mick Schumacher in fifth headed Zhou Guanyu and Kevin Magnussen. Stroll retained eighth despite the spin, keeping him ahead of Yuk Tsunoda and Sebastian Vettel, the last of the drivers to set a lap time before the end of the hour.

Skies were clearing by the end of the session, teasing a dry second practice session, although the rain is forecast to return on Saturday morning and persist into the early afternoon.