The Newport West by-election has passed by, almost unnoticed. The result, a Labour victory, was expected and although both the main parties saw their vote share decrease, there was no significant movement among the various Brexit-motivated challengers below.

“In Newport, we don’t even have that event of journalistic legend – small earthquake, not many dead”, was the verdict of astute Conservative commentator Paul Goodman. “We have a tremor that barely registers on the seismograph.”

But look again and this result held far more significance than is being attributed. It was a dreadful result for Labour; one that should make the party shudder, not just at the thought of a European election, but at a general election too.

Let’s start with the context. By-elections are traditionally an opportunity for voters to kick the government of the day. Two years into a parliament is probably the peak moment for public discontent with the governing party. In such circumstances, an opposition with designs on power should be making a decisive electoral impact.

Cast your minds back to 2012, two years into the Cameron Government. Ed Miliband’s Labour Party triumphed in the Corby by-election with a swing of nearly 13% from the Tories. Many regarded that as a significant result – a sign that Labour were on the march back to power. In the event, the Conservatives won a majority at the subsequent 2015 general election, regaining Corby in the process.

But at the time the defeat was seen as crippling. The contrast with Newport West could hardly be greater. Fair enough, this was already a Labour held seat, so the political dynamics were not the same.

But the outcome – a swing of 2.4% from Labour to the Conservatives – just defies all political logic. If you translated that swing into a national result it would put the Conservatives on 35% and Labour on 29% – a Tory landslide. Of course that is much too crude a translation. But the trend is becoming clear. In every by-election since 2016 there has been a net swing to the Tories.

And let’s consider the political context again. This is a Conservative Government that is widely and rightly regarded, even by its own members, as one of the most shambolic administrations ever to have held office. The worst government ever, as the departing Nick Boles recently described it.

The Prime Minister is a broken figure, denuded of all authority. Her Cabinet is utterly divided. She has suffered over 41 ministerial resignations and seen backbenchers resign from the party. Her government is unable to progress the only policy it has. And yet the Labour party, in a cultural heartland constituency in South Wales, has lost ground to it.

The fact that pro- and anti-Brexit parties failed to make any significant impact in this by-election should be of deep concern to the Labour party. It suggests that Brexit is not the key dynamic that is undermining the party’s performance at the polls. Some other explanation is needed.

Yet despite its electoral weakness Labour can still see a clear path to power – through a divided Conservative party that looks set to rip itself apart over Brexit.