Lucas is one of only two women in the one-person keelboat fleet in Weymouth but she sailed a consistent regatta to claim the Paralympic title by nine points.
Lack of breeze in Portland Harbour meant no sailing was possible on Thursday ensuring that the overnight positions remained and Lucas took podium top spot.
Britain hasn’t won a sailing medal since the sport joined the full Paralympic Games programme at Sydney 2000, although the British sonar team of Andy Cassell, Kevin Curtis and Tony Downs took gold at when the sport was a demonstration event in Atlanta.
"This is definitely the dream," said Lucas.
"I don't think it's sunk in. It's a sense of relief, something so, so special. It will hit me in a few days' time when it all settles down. My dad's cried more than me."
"I've been working hard on boat speed. I had some great starts through the week. I kept it simple.
"Guys hate being beaten up by girls. At the beginning of the week the others weren't too happy. I think they got used to it as the week went on, as I was consistent.
"It's a shame we didn't get a chance to do the final race, that we couldn't celebrate out on the water but it feels like the longest week of my life."
Elsewhere, Alexandra Rickham and Niki Birrell - four-time consecutive world champions - settled for bronze in the two-person keelboat fleet although their was controversy in the three-person sonar.
"We have medalled at every event in the universe," said Birrell.
"We're a little bit gutted we haven't made a gold medal, but life could be worse. We'd obviously have preferred a gold medal, but we've got a medal.
"I'm proud of what Alex and I have done. We're happy to be taking something home. What a fantastic four years we have had, best four years ever".
John Robertson and his sonar crew of Hannah Stodel and Steve Thomas were third heading into the final days competition and would have won bronze due to the race cancellations.
But an off the water row between their bosun Simon Hiscocks, a double Olympic medallist, and race officials led to the deduction of four points, dropping the British crew - competing at their third Games - to fifth.
Norway’s Aleksander Wang-Hansen was the major beneficiary of the penalty, jumping from fourth into bronze while Germany’s Jens Kroker took silver and Udo Hessels dominant Dutch crew gold.
But the manner of their loss left the British crew devastated, after they finished sixth in Beijing and Athens.
Hiscocks was involved in an altercation over whether he should be allowed to clean the port side keel of the three-person keelboat while he was carrying out minor repairs ahead of racing.
He believed he had permission but the race jury ruled he had breached a sailing instruction and imposed a four point penalty, dropping the British crew out of the medal positions.
“I fully regret that my actions have led to this situation and apologise again for any perceived disrespect shown while I was completing the repair on the sonar," said Hiscocks.
"I believe the task I was undertaking was part of the authorised repair, but clearly misunderstood the instructions and in hindsight appreciate that my actions were inappropriate and deeply regret the impact it has had on the sonar crew."
British team manager Stephen Parks claimed the penalty was 'grossly disproportionate to the deemed transgression' and twice unsuccessfully appealed.
"The British team is hugely disappointed that the medals at a Paralympic Sailing event have been determined in this manner for such a minor off-the-water transgression," said Parks.
"We wanted the medals at these Paralympic Games are determined by the talents of the athletes on the water."