It is not often that Nigel Farage finds himself at the centre of a political consensus, but he spoke for Westminster in his analysis of what Ukip’s Rochester victory meant for the general election. “All bets are off,” he declared. “The whole thing’s up in the air.” This has not stopped the political classes fretting over the weekend about What It All Means.

There is one obvious point worth remembering about the byelection: voters were not choosing a government, deciding who goes to No 10, or endorsing or rejecting a manifesto. When they do, the choice before them will be different from the one they faced last week.

My survey in Rochester and Strood, 10 days before polling, found that more than a fifth of Ukip byelection voters said they would either vote Conservative at the general election or that they did not know what they would do – which makes it far from certain that the parliamentary career of Mark Reckless will last beyond next May.

Ukip’s longer-term prospects depend in part on how far it can ape the Liberal Democrats, with whom it has more in common than either party would care to acknowledge. In the 1990s the Lib Dems won a string of byelections at the expense of struggling Conservative governments. Christchurch, Ribble Valley and Eastbourne went straight back to the Tories at the next general election, but the Lib Dems held their later byelection gains – Eastleigh, Newbury and Romsey – in at least two subsequent general elections. Having won in the first place by harvesting protest votes, the Lib Dems established themselves as the Japanese knotweed of British politics through relentless local campaigning. In marginal seats this strategy continues to pay dividends, with many Lib Dem MPs apparently defying a national swing that ought to sweep them away.

Four years ago, with the coalition agreement signed and a new Labour leader in place, Farage himself could not have predicted that the result of the next election would hang on whether his party would score three, four, five, six or seven times its 2010 vote share. But looking back, we can see that the tale of the Emily Thornberry tweet provides a perfect parable for Ukip’s rise. I do not suppose the shadow attorney general was overcome with hostility or even distaste at the sight of a house festooned with St George flags; the problem was that a senior Labour politician seemed bemused by the kind of people her party was created to represent.

But Labour’s Rochester implosion should offer only limited comfort to the Tories, who have their own problems with the aspirational working-class voters that north London Labour finds so exotic. Conservatives like to talk about “the strivers” who share what they like to think of as Conservative values. But as I found in my Blue Collar Tories research in 2012, such people no longer see the party as their natural ally. Rather than helping those who want to get on, the Tories seemed to be for those who had already made it – while in their own lives, anxiety and insecurity were as much a force as ambition.

The fact that the Conservatives are losing voters to Ukip while struggling to attract those who voted for other parties in 2010 suggests they have still not successfully shown what a Conservative government is for. This needs to be done on a broad front in a way that encompasses the economy and public services. For a wavering voter to plump for the Tories next May, they do not have to feel they are already benefiting from an economic recovery and tough decisions on public finances – but they do need to have an idea of what those benefits will be and how they will share in them.

On immigration in particular the Tories have a fine line to tread. Anything they now say about the subject must sound like a convincing plan of action; otherwise they risk simply raising the prominence of an issue they seem unable to do anything about.

Conservatives will be hoping that David Cameron has managed to retrieve the kitchen sink from the Medway shores. He will be needing it.