Independent MP Peter Law's victory in Blaenau Gwent was astonishing - but it was not the first time a Labour rebel beat the odds in a valley heartland.
SO Davies stood against Labour in 1970
Thirty-five years earlier, the octogenarian ex-Labour MP SO Davies also upset the party's applecart, that time in neighbouring Merthyr Tydfil.
Both results suggest traditional Labour voters will readily switch support from the party to a popular local figure.
The unanswered question is whether will they "go home" to Labour so easily.
Mr Law pulled off the shock result of the general election by turning Labour's 19,000 majority into a 9,000-vote majority of his own in the seat he also represents in the Welsh assembly.
But as the new independent socialist MP for Blaenau Gwent prepares to take his seat in Westminster, he can look back at a similar achievement by SO Davies in 1970.
Stephen Owen Davies - always known as SO - had been Labour MP for Merthyr since 1934 when the local party decided he was too old to stand again.
Officially he was 84 at the time, although there were rumours that he was actually closer to 90. But he refused to retire and decided to stand as an independent when Labour chose union official Tal Lloyd as the official candidate to defend his 17,000 majority.
In a striking echo of Blaenau Gwent 2005, the Merthyr 1970 result saw SO romp home as an independent socialist by 7,400 votes.
However, the country never had the chance to see whether SO could repeat his success. He died two years later and at the subsequent by-election Labour regained the seat, albeit against a strong Plaid Cymru vote.
Political commentator Patrick Hannan said one of the reasons he did well was that there had been a dispute at Merthyr's Hoover factory - the town's major employer - and disgruntled workers felt their MP had been badly treated.
"He was, of course, sort of ostracised (by Labour)," said Mr Hannan.
SO Davies' election message in the 1934 by-election when he first became an MP
"But the only time I spoke to him he told me 'I do get the whip, you know'. Unlike Peter Law, they all had been colleagues in Westminster and I don't think they wouldn't speak to him or anything like that.
"He was obviously being given the information he needed and was voting with the Labour Party.
"He was a peculiar figure who referred to himself in the third person. He would say 'SO Davies did this or SO Davies did that.' "
He also looked as if he belonged to a different age, in his parliamentary "uniform" of Homburg hat, silk scarf, black jacket and pin-striped trousers.
"There's a sort of parallel with Peter Law," said Mr Hannan. "They ditch these guys and there's bad feeling. So they say 'We'll show the Labour Party that they can't mess us about."
Mr Hannan believed such victories were "individual events" rather than indicators of wider political upheaval.
"SO and Peter Law are similar in that there is this feeling of 'Look, you people outside can't simply ride roughshod over us and tell us what to do'. They give them (the parties) a shock from time to time.
"In a sense both Peter Law and SO don't have an issue except the ability of constituencies to decide their own candidates."
Glyn Mathias, a former BBC Wales political editor, remembered the difficulty of interviewing the independent Merthyr MP. "I was there for four hours and he only got up to 1935," he laughed.
"The point about SO was that he had been semi-detached for years. He just carried on doing what he'd always done."