Brothers Richard and Peter Chambers with Rob Williams and Chris Bartley took silver today in the lightweight men's four in one of the Games' most exciting rowing races to date.
Behind at halfway they came back in storming fashion before being edged on the line by South Africa by just 0.25 of a second.
"I think we should be celebrating this medal, it's another medal for Team GB but I think we should also congratulate the winners. They are an outstanding crew", said Richard Chambers.
"You can't be upset when you win a silver medal with 30,000 people cheering you on. It was a fabulous experience" said Rob Williams.
"We laid it all down. I couldn't give more and nor could the other three", added Williams.
"We have to thank the whole of Northern Ireland for their support. Winning an Olympic silver medal is great", said Peter Chambers - the younger of the two brothers from Coleraine.
Strokeman Chris Bartley was helped onto the podium after showing signs of physical distress from the effort expended in a scintillating contest.
"The pain was quite extreme and I was physically sick a couple of times. I'm still not feeling tip top but I'll be ok", said Bartley.
"This was an exceptional performance", said GB Rowing Team Performance Director. "It was GB's second ever lightweight Olympic medal. They can be proud of how they performed today".
Britain's other finalists - the mens' double and women's eight - were both fifth.
In the earlier semi-finals both lightweight doubles won in style to book their places in Saturday's finals. Sophie Hosking and Kat Copeland reeled back the fast-starting Greek World Champions to take their victory. Mark Hunter and Zac Purchase, defending Beijing champions, were locked in a battle with the French before succeeding.
They will be joined on Saturday by the men's four of Andrew Triggs Hodge, Tom James, Peter Reed and Alex Gregory who beat their strongest rivals, Australia, to win.
"That was a nice semi-final but it's the final on Saturday that counts", said Triggs Hodge afterwards.
Britain has four boats in tomorrow's finals: the men's pair of George Nash and Will Satch, the men's quadruple scull of Tom Solesbury, Charles Cousins, Matt Wells and Stephen Rowbotham, the women's double scull, featuring double World Champoins Katherine Grainger and Anna Watkins; and Alan Campbell in the men's single scull.
The finals start at 11.30 and run to 12.30.
RACE REPORTS AND QUOTES
What a race the lightweight men's four turned out to be. Denmark blasted out of the blocks and took an early lead just as they had in their semi-final.
Australia took up the lead in the chasing pelota with GB riding at the back. With 1200m gone the GB boat lift itself into contention and showed what a pedigree they have in this event.
They clawed and fought their way back into contention and looked potentially to have timed it just right as they nudged past Australia and then Denmark in the dying metres only to be caught by a surge from South Africa.
"We're delighted with our silver medal", said the younger Chambers (Peter) afterwards. "There were some legendary crews in that race. Denmark got the bronze and the world champions were fourth so a silver is great.
Earlier Britain's young double scull duo of Bill Lucas and Sam Townsend were fifth in a race won by New Zealand - who put in a fantastic second half to take the victory.
The British duo were second after 500m but slipped back in the second half of the race.
Britain's women's eight of Natasha Page, Louisa Reeve, Olivia Whitlam, Lindsey Maguire, Jess Eddie, Katie Greves, Vicky Thornley and cox Caroline O'Connor were clearly disappointed with today's final which saw them come home in fifth place ahead of Australia in a race won by the USA, the defending champions, with Canada and the Netherlands taking second and third.
"It wasn't the way we wanted our Olympics to finish", said Jess Eddie.
"It was a better race than we've had so far here", said Whitlam.
The men's four of Andrew Triggs Hodge, Peter Reed, Tom James and Alex Gregory were in contention with their big Aussie rivals throughout the first 1500m of today's semi-final and, from there, pounced to take a semi-final victory in 5:58.26.
The same two crews are likely to contest the honours in Saturday's final so today had the feel of a dress rehearsal about it. Great Britain got their lines perfect but know that anything can happen on show "night".
So whilst Andy Hodge in the stroke seat, upped the rate and carved a route past Australia today in the final phases there is still a compelling final in store which on today's evidence looks set to go to the wire with the British crowds hoping for a show-stopping performance from the British quartet.
Behind Australia and Britain, the Dutch led the chasing pack and took the third qualifying slot.
James said: "We did a good job today. But we will need to perform better in the final, we know that. We did a good job in our boat we don't know what was happening in theirs".
"That was a nice semi-final", said Triggs Hodge. "But the final is the only on that counts.
Reed said: "It was a lot of pressure today but I felt alive on the start. I was really buzzing. But I'm not going to go home and jump around for joy and say we've done it.
Gregory said: "Our first job was to get into the final here and we've done that. It will be my first Olympic final which is great. There is only one race in the four years that really counts and that's the final here".
Next for GB, on the by now bobbly course in breezy and unsettled conditions, at Eton-Dorney were the lightweight women's double scull of Sophie Hosking and Kat Copeland. They, too, settled into a strong and steady rhythm and were not spooked by the early charge out front from the World Champions.
Stroke by stroke they pulled back on them, overhauling Germany in the process, to come through to hit the front and win. Their progress since the Munich world cup has been nothing short of remarkable. it also means that another piece of GB rowing history was made on the Eton-Dorney course as the duo became the first British women's lightweight double to make a Games final.
Hosking said: "Having raced them [The Greeks] over the years I knew that would be their race plan. But we were confident that we could find our rythmn.
Having won multiple medals in world cups and World Championships in the last four years it had to be my ambition to get to the Olympic final but I didn't underestimate the task. Now we can enjoy the next few days and enjoy every minute of the final".
Copeland said: "I was thinking this morning that at the beginning of the year I didn't even know if I would make it into the double but now I'm in an Olympic final. It's unbelievable really".
All eyes in the crowd settled next on the mercurial duo of Zac Purchase and Mark Hunter in the lightweight men's double scull. Theirs has been a topsy-turvy season with some flashes of brilliance and some troughs of, by their standards, mediocrity.
Today the Olympic and World Champions were tucked behind France in the opening phases of the race before picking their moment and rattling through, buoyed by the booming of the crowd, to win in 6:36.62
Their performance rounded off the semi-final stage with all 13 GB boats in the Olympic regatta having qualified for the finals in a great show of consistency.