Great Britain has collected its first gold medal of the London Games after Heather Stanning and Helen Glover won the coxless pairs with a stunning performance that will spark a mass outpouring of celebration and relief across the country.

One had never stepped in a rowing boat until 2008, the other will return to serve in the Royal Artillery in September. But Glover and Stanning will now go down in the record books as Gold medalists Heather Stanning and Helen Glover became the first homegrown gold medallists of the London 2012 Olympics.

Not only that but, in their first Olympics, they have made British sporting history as the first female rowing gold medal winners in a sport that has reliably delivered over the years.

Afterwards, Stanning said: "I'm shattered and ecstatic at the same time. In all our races this season, we've got out ahead and tried to stay there." Glover added: "It shows if you work hard, you can do anything."

In lane three, Stanning and Glover went out fast alongside the German boat and were clear by the 500m mark. Graceful, settled and focused, they stretched their lead and dominated the race to a wall of sound.

They were three-and-a-half seconds and three-quarters of a length clear at the halfway mark. By 1500m, they were five seconds clear and the pair allowed themselves a smile.

Facing the twice Olympic champions in lane one from Romania and the twice world champions from New Zealand, they dominated the race from start to finish and sealed victory in 7:27.13 in front of Australia and New Zealand.

At an overcast Eton Dorney, roared on by a capacity crowd including Prince Harry and Prince William, the volume rose as they entered the final stages.

Stanning, who was commissioned from Sandhurst in 2008 and has served in Aghanistan, is not the first solider to bail out the organisers at these Games but will be among the most celebrated.

And her success with Glover, a product of the National Lottery-funded Sporting Giants talent identification programme, will also spark relief among British officials who were starting to fret a little about hitting their target of equalling fourth in the medal table from Beijing.

A relatively disappointing performance to date from Britain's swimmers, plus the crushing disappointment of Mark Cavendish's failure to win the cycling road race on Saturday, have led to some frayed nerves. Lizzie Armitstead's silver in the women's road race and a surprise bronze for the male gymnasts had helped, but there was a growing craving for the first gold.

It has taken until the fifth day, but the success of Glover and Stanning will build the national mood ahead of a hoped-for avalanche of medals over the weekend, as the rowing finals come thick and fast, the track cycling begins and the medals are handed out in the sailing.

The pair, relatively unheralded when they were put together in a pair by the Team GB Start coach Paul Stannard and coached by Robin Williams, went on to win silver medals at the world championships in 2010 and 2011 behind New Zealand and are unbeaten this season.

That second world championships defeat, in Bled, was by just 0.8sec and has fuelled their desire to avenge their defeat at these Games and they have won gold at all three World Cup races this season. They were hot favourites for the final after winning their heat in the fastest time.

Glover, a former PE teacher in Bath, was part of the England hockey set up before being spotted by Sporting Giants, a scheme designed to find untapped talent in rowing, volleyball and handball.

In 2008, she was one of 4,500 hopefuls being tested in groups of 200 having never set foot in a rowing boat.

"I remember sitting in a room in Bisham Abbey and someone saying: "A gold medallist in 2012 could be sat in this room. Look around you'," she has said.

"I thought: 'Right, I'm going to make that me.' It was quite surreal."

Having been identified as having the physical and sporting attributes that could make her a top class rower, she was developed by British Rowing's Start programme – a key priority of the performance director David Tanner.

Developing Britain's female rowers has been a key area of focus since 2004, although a hoped-for gold narrowly failed to materialise in Athens or Beijing. The week that Glover tried out for Sporting Giants, the Beijing Games were on television. Now she is the one in the spotlight.

When they were selected to the British team last month, Glover told the Guardian: "Everyone assumes that she is the one doing the calls and the shouting. But I'm the bossy one, I sit behind her."

Glover also paid tribute to her partner. "Heather's incredibly strong, incredibly good technically and very, very reliable. I have got a clear idea of what I want, which is an ideal situation," she said.

"What you want from a stroke person is ultra-reliability and it just gives you added confidence going into a race. The more you can rely on that, the more you can be sure that what you've written down the night before will play out on the water."

On Wednesday, it could not have gone any better had they scripted it.