Hannah Mills and Saskia Clark won silver in the women's 470 class on Friday afternoon.
Having seen Australia deny Luke Patience and Stuart Bithell top spot in the men's 470 class earlier, the world champions were pipped to the gold medal by New Zealand's Jo Aleh and Olivia Powrie.
Mills and Clark entered the medal race top of the standings alongside Aleh and Powrie, although it was the New Zealand pair that won the race and took the gold medal as Britain collected their fourth sailing silver of London 2012.
Mills and Clark came into the race guaranteed of winning a medal due to their points tally after the opening 10-race series. They were assured of silver as long as they were not disqualified or black flagged in the medal race, which they began impressively.
The Kiwis tacked off at the start due to pressure from the Britons, which saw the rivals end on opposite sides in the first leg.
Unfortunately for Mills and Clark, it was the right side that paid and they were on the left so could only watch on as Aleh and Powrie powered ahead. The New Zealand pair rounded the first mark in the lead, with one minute 13 seconds separating them and the 10th-place Brits.
As the wind all but disappeared, Aleh and Powrie moved into an almost unassailable lead - two minutes 22 seconds ahead around the second mark.
Mills and Clark saw their chances cut even further as the race officials chose to shorten the course due to the lack of wind. It meant less distance for the British pair to catch the Kiwis, who went on to win the medal race and secure gold.
Britain won silver, while the Netherlands' Lisa Westerhof and Lobke Berkhout took bronze ahead of France's Camille Lecointre and Mathilde Geron.
"I think we just feel a bit gutted at the moment that we didn't even put a good show on, really," Clark told BBC Sport. "We had the Kiwis at the start line and then we let them go to the right and didn't follow them."