One tweeted picture saw Labour MP Emily Thornberry go from the shadow cabinet to the butt of a twitterstorm, jokes and resignation. Here's how events unfolded, driven by social media.
The spark - 15:12 GMT
There was minimal description of the image in the tweet composed by Emily Thornberry, who had travelled to Rochester to campaign in the by-election. But if a picture ever prompted a thousand words, it was this one.
The hash-tags sprung up instantly. Islington, Ms Thornberry's parliamentary seat, became less a borough than an abstraction, furthering a perception, according to Simon Danczuk, the Labour MP for Rochdale, that the Labour Party "has been hijacked by the north London liberal elite".
The S-word - 15:13
Tories lick their lips
Communities Secretary Eric Pickles was first in with the knife, saying: "We should have pride in flying the Cross of St George - don't knock the national flag of England."
Prime Minister David Cameron also appreciated the free hit, saying the Labour MP's actions were "completely appalling" and suggesting that she was "sneering at people who work hard, are patriotic and love their country".
Backpedalling - 18:15
Emily Thornberry told Mail Online: "It was a house covered in British flags. I've never seen anything like it before."
"It had three huge flags covering the whole house. I thought it was remarkable. I've never seen a house completely covered in flags."
On Friday, Peter Spence of the Daily Telegraph helped her out - perhaps - by highlighting a previous picture she tweeted in 2012.
The BBC's Ross Hawkins noted that the Sun's front page was a "nightmare" for Labour, and posed three questions.
Damage done - resignation announced 22:30
Shortly after the polls closed in Rochester it was reported that Ms Thornberry had resigned from the shadow cabinet.
Throughout Thursday she spoke twice to Labour leader Ed Miliband, who was said to be "furious" that the tweet had tripped Labour up on a day when the Tories' loss to UKIP was supposed to dominate the news cycle.
Mr Miliband agreed it was best that Ms Thornberry resign.
Backlash to the backlash
Was Emily Thornberry hard done by?
Labour MPs from John Mann to Douglas Alexander seem to think not, having lined up to denounce the tweet and say it was right for Ms Thornberry to resign.
Twitter founder Jack Dorsey was asked on Friday if the events surrounding Emily Thornberry's tweets made him frightened at the power of the medium he created.
He answered: "I don't think it's any different from what we've been doing as a humanity - it's just faster."