Olympic champion Helen Glover and her Great Britain team-mate Polly Swann took gold in the women's pair at the World Rowing Cup at Eton Dorney.
Glover, back at the scene of her London 2012 victory, and Swann fought off a late challenge from New Zealand to win by a length, with Germany third.
"It's amazing being back here. Eton Dorney is the place to be for rowing right now," said Glover, 27.
Britain also won golds in the women's double sculls and the men's eight.
Victoria Meyer-Laker and Frances Houghton won their final, while Britain held off Poland in a thrilling finish to the men's eight.
Glover and Swann were comfortably clear at the 1,000m halfway mark, but had to withstand a strong, late challenge from New Zealand.
"The Kiwis were doing everything they could, but I think we were both confident of dealing with anything they could throw at us," said Swann.
"It was pretty blowy out there and they were challenging conditions."
Last summer, Glover and Heather Stanning became the first British female rowers to win an Olympic title by clinching their country's first gold of the London 2012 Games.
Britain also won four silvers and two bronzes on the final day of the regatta.
Brothers Richard and Peter Chambers finished second behind Poland in the lightweight men's double sculls, while Kathryn Twyman and Imogen Walsh took silver in the women's lightweight doubles.
Alan Sinclair, Nathaniel Reilly O'Donnell, Scott Durant & Matthew Tarrant were runners-up in the men's four and there was silver for Alan Campbell in the men's single scull.
Bronze medals went to Bill Lucas and Matt Langridge in the men's double sculls and the lightweight men's four of Adam Freeman-Pask, William Fletcher, Jonathan Clegg and Chris Bartley.