[1] Champions in 1978, March expanded to seven works cars, all new ground effects 792 models powered by BMW 4-cylinder engines and running on Goodyear tyres.
1978 runner-up Marc Surer started as pre-season favourite; his team-mates would include Beppe Gabbiani, Ricardo Zunino, Miguel Ángel Guerra and Teo Fabi.
Osella would be running a BMW-engined in-house car (albeit using a four-year-old design penned by Giorgio Stirano, renamed the FA2/79) for Eddie Cheever; their main strength was an exclusive deal for Pirelli tyres.
Chevron hired experienced Formula 1 designer Tony Southgate to create the B48 ground effects car with Paul Owens, based on the 1978 B42 chassis.
AGS continued to run their 1977 car, with Alain Couderc driving; Pilbeam's MP42 would be driven by Patrick Nève, Maurer employed Armin Hahne and AMS ran Piero Necchi.
The race - now bearing the BRDC International Trophy name - took place in heavy rain, allowing Cheever to demonstrate Pirelli's wet weather superiority in the well-tested Osella-BMW.
Standing in for the absent Daly (driving for Ensign at the US West Grand Prix), Keke Rosberg started 3rd and took a dominant win some 27 seconds ahead of Dougall, Guerra, Henton (struggling with damaged rear suspension), Cheever (having chosen the wrong tyre compound) and Fabi; .
Dougall took a shock victory in the BARC Philips Car Radio International - and the points lead of the series - despite having to switch to the Toleman team's old March 782 after problems with the new Ralt.
A late challenge was mounted by spirited pole-sitter Rosberg (again covering Daly's F1 commitments), who approached the track's F1 lap record before his throttle jammed open and his ICI March was destroyed at the same corner which claimed team-mate South.
Wet weather again allowed Cheever's skill and Pirelli's grip to come to the fore, the American taking a comfortable victory after colliding with Daly when challenging the Irishman on lap 30; the March was forced into retirement.
Gabbiani finished 3rd from Gaillard, Surer (two points seeing him move ahead of Henton in the table; the British driver fell out of contention in the race with gearbox trouble) and Rahal.
Hastily arranged as a replacement for the cancelled race at Nogaro, the Dutch track's abrasive surface handed an advantage to the Pirelli-shod Cheever, who promptly won his 3rd victory of the year to leapfrog to the top of the table.
Toleman's Rory Byrne had substantially revised the Ralt over the summer break between rounds 8 and 9, and it looked like his work had borne fruit with Henton winning at Enna after a furious battle with Elgh.
Elgh was followed home by Daly (delayed by the first corner incident), South (despite a stop to replace a damaged nosecone), Fabi, Cheever and Dougall promoted to 6th after Henton's disqualification.