Despite steady morning drizzle, Hill was the only driver among the top nine to take the start on wet-weather Goodyears and had qualified his West Surrey Racing BMW 330e M Sport in fourth position.
But he was already effectively up to third by the start, after poleman Mikey Doble inexplicably emulated an identical gaffe at the same venue from Laurent Aiello in 1999 when he went past the grid onto a second green-flag lap – he therefore had to start his Power Maxed Racing Vauxhall Astra from the rear of the pack.
Hill launched between the only remaining front-row man, WSR BMW team-mate Colin Turkington, and third qualifier Tom Ingram’s Excelr8 Motorsport Hyundai i30 N.
By the end of the opening lap, Hill was 3.4 seconds in front of Ingram, who along with the other slick-shod starters was beginning a freefall down the field.
A spin at Becketts on the third lap preceded a pitstop for Ingram at the same time as championship leader Ash Sutton at the wheel of his Motorbase Performance Ford Focus.
The duo rejoined off the lead lap and finished 22nd and 23rd respectively, just half a second apart, meaning the championship gap between them remains at 42 points.
The race settled down with Andrew Watson in second place in his PMR Vauxhall, while Dan Rowbottom displaced Motorbase Ford team-mate Sam Osborne for second on lap three.
Watson trimmed the gap to Hill from over four seconds to 3.5s but began to come under pressure from Rowbottom.
Source: Autosport