Ukip has delivered the first tremors of the political earthquake promised by Nigel Farage as the party weakened Labour's grip in its northern heartlands and caused the Conservatives to lose control of at least eight flagship councils.

Labour pulled off coups by winning David Cameron's favourite London council, Hammersmith and Fulham, as well as Redbridge, Merton and Cambridge. But outside the capital, it struggled to make expected gains in key targets such as Swindon, Walsall, Tamworth and Portsmouth, while losing Thurrock to no overall control because of Ukip votes.

Farage also ate into Conservative strongholds, causing the party to lose control of eight councils, including Maidstone, Southend-on-Sea, Castle Point, Basildon and Brentwood – the constituency of the local government secretary, Eric Pickles.

By 7am on Friday, with more than 100 of the 172 councils up for election in England and Northern Ireland still to declare, the Tories had lost 102 seats, Labour had gained 94, the Lib Dems had lost 83, Ukip had gained 86, the Greens had gained one and other parties were up seven.

The results of the European parliament elections, which also took place on Thursday, will be announced on Sunday, but the swell in votes for Ukip indicated that it was likely to have been a closely run contest with Labour for first place.

The biggest collapse in the share of the vote for the local elections appeared to be for the Liberal Democrats. The party lost Portsmouth council and looked set to lose Kingston to no overall control.

Ukip did not appear to have broken through in London, where it was polling in single digits, but the party took more than a third of the vote across some wards in Essex and big cities including Birmingham and Hull, where it previously had little or no presence. In Rotherham, Ukip is the official opposition after winning 10 seats and ousting several prominent Labour councillors including the deputy leader of the council.

Farage said it was a "very good night" as the party was now making an "imprint" in local government. He said the Ukip "fox" was now in the "Westminster hen house".

Wakeup call for Labour

Ed Miliband campaigning in Bloxwich leisure centre, Walsall. Photograph: Christopher Furlong/Getty Images

The early results indicated that the Labour leader, Ed Miliband, would face intense criticism during the next 48 hours, including over his personal performance and his appeal to working-class voters. Questions within the party are likely to focus on whether his campaign strategists realised early enough that Ukip posed a threat to Labour as much as to the Conservatives.

Douglas Alexander, the shadow foreign secretary and Labour election co-ordinator, said there were "grounds for optimism" in key target seats and that the party was well-placed to win the general election next May.

But the night was described as a wake-up call for the main political parties by John Healey, Labour MP for Wentworth and Dearne.

"People are angry. They are saying they aren't hearing enough of what they feel in what we politicians are saying," he said. "For me today was compounded when I was out knocking on doors and one man, a lifelong Labour voter, said to me: 'John, I'm voting for Ukip today. You all need a kicking.'"

In Labour target seats further south and east, such as Portsmouth, a strong Ukip vote was destroying the party's hopes of making more than 400 council gains.

The leader of the Labour group in Portsmouth, John Ferrett, said Ukip's performance was "causing mayhem". Labour also suffered a blow in a key election battleground after the Conservatives held on to Swindon, days after Miliband embarrassingly failed to recognise the name of the party's group leader in the borough.

But the man in question, Jim Grant, said Miliband's gaffe had not had an impact on Labour's disappointing showing in the Wiltshire town.

"That's a big media event. I don't think it has affected what has happened here. I'm a big fan of Ed but we have all got to work harder to get our message across."

Labour had hoped that the council would at least slip into no overall control. In fact, the Tories ended up with 30 seats to Labour's 23 and the Lib Dems' four.

Both the Conservatives and Labour will have to think deeply about whether they can win back the Ukip vote, with some rightwing Tory backbenchers urging Cameron to think how they can reunite the centre-right through some form of Ukip-Tory pact.

The Labour MP Graham Stringer, a longstanding critic of party leaders, issued a savage attack on the quality of the Labour campaign, saying it was "unforgivably unprofessional", and asked why his aides had been unable to tell Miliband the price of bread.

Liberal Democrat wipeout

Nick Clegg on his way to vote in the elections in Sheffield. Photograph: John Giles/PA

The Lib Dems were also braced for a poor performance, in a sign of how the burden of pain is being shared across Westminster. The business secretary, Vince Cable, admitted it was going to be a difficult night for the junior party in the coalition.

He said the Lib Dems would take a "kicking" for being in government as he appeared to distance himself from Nick Clegg by saying the party leader had decided to focus the Lib Dem campaign on the EU. Speaking on Sky News, Cable said: "The party leader took the gamble of fighting a European election on the issue of Europe, which is a very unusual thing to do in the UK. We'll see."

Cable said that all the main parties would suffer poor results. But he added: "We are in government. We take a kicking for the things that government does that are unpopular. It does reflect on us."

He said he had not been comfortable about forming a coalition with the Tories. "We put personal preferences aside and deal with it professionally … We have done massive things in government. We have risen to the challenge."

One longstanding critic of Clegg, the former Lib Dem MP Lembit Opik, called for him to go as the very first results showed the party's vote had collapsed, even though it was holding some wards in Lib Dem constituencies in Birmingham and Redcar.

Lynne Featherstone, the Lib Dem international development minister, said Ukip's "stunning success" was a protest at the dissembling of the political class. She added: "We are so guarded and so on message that we have lost our humanity. We are the whipping boy of the coalition."

Tories look towards Newark byelection

David Cameron and his wife Samantha. Photograph: Matt Dunham/AP

Cameron, once thought likely to face the most turbulent backbench response of the three party leaders, was increasingly confident that the Conservatives would not turn in on themselves, but would instead focus on winning the Newark byelection on 5 June, caused by the resignation of the former Tory MP Patrick Mercer, in an attempt to show that the Ukip bubble could be burst.

But the prime minister will have to endure the possibility that Ukip will be able to claim on Sunday night that it has achieved its main political objective of winning the poll in the European parliamentary elections.