David Millar won the two-up sprint to claim his first individual stage victory at the Tour de France since 2003.
The 35-year-old was the best of a five-man break at the end of the 226km 12th stage with Jean-Christophe Peraud (AG2R La Mondiale) second and Egoi Martinez De Esteban (Euskaltel - Euskadi) five seconds off the pace in third.
Millar is the fourth British rider to claim a stage win at this year's race and his victory coincides with the 45th anniversary of Briton Tom Simpson's death in the race.
There were no changes to the general classification, which Sky's Bradley Wiggins leads ahead of teammate Chris Froome and Italian Vincenzo Nibali (Liquigas-Cannondale).
Millar was part of an original 19-strong breakaway that escaped within the first 20km of the undulating 226km run from Saint-Jean-de-Maurienne to Annonay Davezieux.
The front group had whittled down to the race definitive five, which included Cyril Gautier (Europcar) and Robert Kiserlovski (Astana), by the second category one climb of the stage - the Col du Granier.
A series of counter-attacks saw riders lose contact with the peloton. Green jersey leader Peter Sagan (Liquigas-Cannondale) was among those who tried to bridge the gap to the leaders, but his efforts were in vain.
Orica-GreenEdge rode to the front and reeled the 22-year-old and his companions in with the interests of its maillot vert contender, Matt Goss in mind.
The peloton shortly after allowed the time gap to the race leaders to blow out with some 117km remaining. The grupetto that included world champion Mark Cavendish, eventually made contact in what, after an aggressive start, essentially became a transition stage for the yellow jersey group.
The escapees achieved a maximum time advantage of 12 minutes and 50 seconds.
In the points competition, Goss won the bunch sprint at the intermediate check, ahead of Andre Greipel (Lotto-Belisol), further closing the gap to Sagan. The 25-year-old Australian beat his Slovak rival at the finish winning the bunch sprint for sixth but was later relegated to seventh and docked 30 points for deviating from his line.
Tour de France 2012, stage twelve: St Jean de Maurienne - Annonay Davézieux, 226km
1. David Millar (GBr) Garmin Sharp in 5h 42' 46"
2. Jean-Christophe Peraud (Fra) AG2R La Mondiale at st
3. Egoi Martinez (Esp) Euskatel - Euskadi at 5 sec
4. Cyril Gautier (Fra) Europcar
5. Robert Kiserlovski (Cro) Astana all at st
6. Peter Sagan (Svk) Liquigas-Cannondale at 7-53
7. Matt Goss (Aus) Orica-GreenEdge at st
8. Sébastien Hinault (Fra) AG2R La Mondiale at 7-54
9. Cadel Evans (Aus) BMC Racing
10. Luca Paolini (Ita) Katusha all at st
Overall classification after stage twelve
1. Bradley Wiggins (GBr) Team Sky 54h 34' 33"
2. Chris Froome (GBr) Team Sky at 2-05
3. Vincenzo Nibali (Ita) Liquigas-Cannondale at 2-23
4. Cadel Evans (Aus) BMC Racing at 3-19
5. Jurgen Van Den Broeck (Bel) Lotto-Belisol at 4-48
6. Haimar Zubeldia (Esp) Radioshack-Nissan at 6-15
7. Tejay Van Garderen (USA) BMC Racing at 6-57
8. Janez Brajkovic (Slo) Astana at 7-30
9. Pierre Rolland (Fra) Europcar at 8-31
10. Thibaut Pinot (Fra) FDJ-BigMat at 8-51
David Millar heads the escape group
David Millar wins
Tour de France 2012: Latest news
Froome explains his attack on La Toussuire
Nibali fails to crack Sky but pleased with Tour mountains performance
Roche ready to achieve career-long Tour top ten ambition
Wiggins: 'I'm not some s**t rider that's come from nowhere
Nibali hits out at Wiggins after Tour frustration
Cavendish enjoying new Tour role
Wiggins taking nothing for granted in 'dream scenario'
Sky keeping Tour focus on Wiggins
Di Gregorio arrested by police at Tour de France
Tour de France 2012: Teams, riders, start list
Tour 2012: Who will win?
Tour de France 2012 provisional start list
Tour de France 2012 team list
Tour de France 2012: Stage reports
Stage 12: Millar wins Tour stage nine years from his last
Stage 11: Wiggins strengthens Tour lead as Evans slips back
Stage 10: Voeckler wins and saves his Tour
Stage nine: Wiggins destroys opposition in Besancon TT
Stage eight: Pinot solos to Tour win as Wiggins fights off attacks
Stage seven: Wiggins takes yellow as Froome wins stage
Stage six: Sagan wins third Tour stage
Stage five: Greipel wins again as Cavendish fades
Stage four: Greipel wins stage after Cavendish crashes
Stage three: Sagan runs away with it in Boulogne
Stage two: Cavendish takes 21st Tour stage victory
Stage one: Sagan wins at first attempt
Prologue: Cancellara wins, Wiggins second
Tour de France 2012: Comment, analysis, blogs
Analysis: What we learned at La Planche des Belles Filles
Analysis: How much time could Wiggins gain in Tour's time trials
CW's Tour de France podcasts
Blog: Tour presentation - chasing dreams and autographs
Comment: Cavendish the climber
Tour de France 2012: Photo galleries
Stage 12 by Graham Watson
Stage 11 by Graham Watson
Stage 10 by Graham Watson
Stage nine by Graham Watson
Stage eight by Graham Watson
Stage seven by Graham Watson
Stage six by Graham Watson
Stage five by Graham Watson
Stage four by Graham Watson
Stage three by Graham Watson
Stage two by Andy Jones
Stage two by Graham Watson
Stage one by Graham Watson
Prologue photo gallery by Andy Jones
Prologue photo gallery by Roo Rowler
Prologue photo gallery by Graham Watson
Tour de France 2012: Team presentation
Sky and Rabobank Tour de France recce
Tour de France 2012: Live text coverage
Stage 10 live coverage
Stage nine live coverage
Stage six live coverage
Stage five live coverage
Stage four live coverage
Stage three live coverage
Cycling Weekly's live text coverage schedule
Tour de France 2012: TV schedule
ITV4 live schedule
British Eurosport live schedule
Tour de France 2012: Related links
Brits in the Tours: From Robinson to Cavendish
Brief history of the Tour de France
Tour de France 2011: Cycling Weekly's coverage index
1989: The Greatest Tour de France ever
Thank you for reading 20 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1