Finn sailor Mills got the better of overnight leader and Palma World Cup winner Giles Scott to claim his first ever World Cup victory, while Fletcher and Sign picked up their first World Cup win as well in the 49er class.
Helena Lucas and Megan Pascoe had opened up the medal tally for the British Sailing Team on Friday, with a silver and a bronze from the 2.4mR Paralympic class, but yesterday was the turn of the Olympic Classes sailors in the series of double-points scoring make-or-break medal races.
Bryony Shaw got the day off to winning ways for the Brits, and secured an early birthday present for herself in the RS:X women's windsurfing event, finishing second in the first of her two medal races, before closing out the gold in style with a win in the final race.
"I'm really happy!" said Shaw afterwards, ahead of her 30th birthday tomorrow.
"I didn't have the best of days yesterday on the last day of finals series, so was pretty fired up coming in to today. Two of my main rivals were over the line in the first race, so that was a big opportunity for me.
"I sailed really well, got good starts, and made some good decisions so it's great that it all came together today when it mattered," she commented
"I've had a great start to the year with silver at the World Championships and silver in Palma. I really wanted to keep that momentum going this week and come away with gold, so I'm really happy, and especially to have performed well across the range of conditions this week."
Andrew Mills overturned the six point lead that teammate and Palma World Cup Giles Scott had coming into the final day of the Finn class to claim his first World Cup series victory and 'show some intentions' at the start of this Rio 2016 cycle.
The 27-year-old Mills took the race win in the first medal race of the day to narrow the gap to just two points over Scott, with the pair assured of finishing no worse than second with the final race to go.
Whichever sailor beat the other on the water would take the gold, and today it was Mills's turn to celebrate. He crossed the line in third, with Scott coming home in in tenth to settle for silver.
"With the double medal race, if you'd had a bad first one then any of eight people could have still win gold so it was important to get the job done with a win in the first one," Mills explained.
"Then it was just down to me and Giles. We had a little match race and I got the better of him."
"It feels great," Mills said of his victory. "It's really impressive how the winter training has paid off and it's a great start to the rest of the season with a first ever World Cup win, so it's brilliant.
"It's a good way to start the cycle and show some intentions."
Fellow British sailors Ed Wright and Mark Andrews were also in Finn medal race action, and ended their regattas in seventh and ninth respectively.
After a three-hour wait for suitable conditions, the 49er medal racing finally got underway.
Three British boats were in the top three positions heading into the three double-points races, with Dave Evans-Ed Powys leading the field, Dylan Fletcher-Alain Sign in second and Stevie Morrison-Ben Rhodes in third.
Fletcher and Sign finished all three races inside the top three to overtake teammates Evans and Powys in the overall standings, and claim their first regatta victory.
"It's a huge confidence boost – for us our first World Cup win is wicked," said Fletcher.
"In Palma we were down a little bit, and we've come back fighting here, so we're really chuffed with what we've achieved. Thanks to Paul and Ian, our coaches, for helping us through the week," added Sign.
The day so nearly ended with the British trio on the podium, with Evans and Powys taking silver, but Spain's Carlos and Anton Paz spoiled the party, ousting Morrison and Rhodes from the podium spots by just one point.
Fletcher praised the British strength in the class this week: "It's the best training environment you could have."
"We've worked closely with Dave and Ed recently and they were second so that was great to see, and Stevie just missed out just on the last race, but the Brits were definitely showing quite a strong force here in Hyeres."
Fletcher's partner Charlotte Dobson was not to be outdone in the medal stakes and claimed her first podium finish, along with crew Mary Rook, in the new 49erFX class – a first British medal in the new women's skiff for Rio.
Dobson and Rook went into the day in the silver medal position, and scores of 3,5,4 from the day was enough to keep them there, while Penny Clark and Sophie Ainsworth ended their regatta in seventh.
Alison Young made it two World Cup podium spots in a row, adding Laser Radial bronze to her gold in Palma, while Sophie Weguelin and Eilidh McIntyre also made it two World Cup medals from their debut regattas as a team claiming a hard-fought bronze in the 470 Women's event after starting the day in fourth overall.
Ben Saxton and Hannah Diamond missed out on a first British medal in the new Nacra 17 class by the narrowest of margins – they finished fourth, just two points from the bronze medal, while teammates Lucy Macgregor and Tom Phipps ended their regatta in tenth.
Luke Patience and Joe Glanfield were unable to improve their standing in the 470 Men's event.
Called over the line early in the first medal race of the day, they finished tenth in the second to end their second regatta together in ninth overall, while Nick Thompson was also ninth in the Laser class.
"It's year one of the cycle, so it's dangerous to draw too many conclusions at this stage, but we've had some great performances across the team this week," said RYA Olympic Manager Stephen Park.
The highlights would be our first World Cup wins for Dylan and Alain in the 49er and for Andrew Mills in the Finn, and also the development of some of our younger sailors and the progress that's being made in the new classes.
"A first medal in the 49erFX is great for Charlotte and Mary but reflects well across everyone in the programme as those sailors are operating in a rotational system at the moment. Sophie and Eilidh should also be pleased that they've managed to get onto the podium in both of the regattas that they've sailed together."
Bryony Shaw (RS:X Women), Andrew Mills (Finn), Dylan Fletcher & Alain Sign (49er).
Helena Lucas (2.4mR), Giles Scott (Finn), Charlotte Dobson & Mary Rook (49erFX), Dave Evans & Ed Powys (49er).
Megan Pascoe (2.4mR), Alison Young (Laser Radial), Sophie Weguelin & Eilidh McIntyre (470 Women).