Laura Smith, the Labour frontbencher who resigned in the biggest parliamentary revolt Jeremy Corbyn has faced since he became leader, has defended her decision to vote against remaining in the European Economic Area.

Labour’s divisions on Europe broke out into the open on Wednesday night when, in an extraordinary breakdown of discipline, more than half the party’s backbenchers defied the party whip.

In a vote on a Lords amendment that would in effect mean staying in the EEA, 75 backbenchers defied party instructions to abstain and voted for the EEA. A further 15, also defying the party whip, voted against.



EU withdrawal bill: which Labour MPs rebelled over the EEA amendment? Read more

Smith, the now former shadow Cabinet Office minister who had backed remain in the referendum and won her leave-voting Crewe and Nantwich seat by a majority of just 48 in last year’s election, said her first duty was to her constituents.

She told BBC Radio 4’s Today programme that staying in the EEA would not be in their interest, and she refused to accept that if she thought Brexit was a mistake she should say so.

“I think a bad idea is giving people a choice and then telling them they’re wrong. I think that is against democracy ... and we need to understand the reasons why people voted in the way that they do. And, no, I’m not then telling people that voted to leave that they’re wrong. It’s my job to understand why they voted to leave and fight to make their lives better.”

In a week at Westminster that has been dominated by the sense that the Brexit debate and the UK’s future relations with the EU are approaching a crisis, many Labour MPs were frustrated at the frontbench attempt to fudge away party differences.

The shadow Brexit secretary, Keir Starmer, had said on Monday that the party was too divided to pursue the so-called Norway option of EEA membership.

But rebelling on the bill for the first time on Wednesday, the former shadow foreign secretary Hilary Benn, who chairs the Commons cross-party Brexit committee, said there came a point where “we have to stand up and be counted”.

He said that remaining in the EEA, which would include membership of the single market, was not a perfect solution but it was better than all the others. Pointing out that the other options proposed by the government and by Labour were only untested proposals, Benn said the EEA was an established alternative to EU membership.

“It has the one great advantage – it at least looks like a lifeboat. And the closer we get to October, the less inviting the cold sea appears.”

Laura Smith MP (@LauraSmithMP) I will not vote for any amendment to Brexit legislation that does not deliver the exit from the European Union that my constituents voted for.

In addition to Smith’s departure, five parliamentary aides resigned before the vote: the parliamentary private secretaries Ged Killen, Ellie Reeves, Tonia Antoniazzi, Anna McMorrin and Rosie Duffield.

Duffield – who won the seat of Canterbury in 2017’s most shocking result – resigned in order to back EEA membership.

But whips were relieved that there were not more rebels. A week ago reports of as many as 120 were being touted, while the New Statesman reported that the leading Labour remainer Chuka Umunna was talking openly of starting a new party, Back Together.

Ged Killen (@Gedk) This evening, I have resigned as Shadow Defence PPS to vote in favour of the Lords EEA amendment. I have always said as an MP I will put the interests of my constituents first and I believe that means voting to maintain the closest possible relationship with the EU after Brexit. pic.twitter.com/biMsQbSkPT

One rebel claimed the result suggested that there would be a majority for an EEA-type amendment to either the trade bill or the customs bill, both of which will be back in the Commons in the next few weeks. With three Tory MPs voting for the EEA amendment and eight abstaining, there is already a core of Conservative dissidents and a customs union amendment is gathering cross-party support.

The shadow chancellor, John McDonnell, anticipating the revolt, admitted in a speech on Wednesday morning that the party was walking a tightrope.

“We campaigned for remain but many of our MPs, including myself, now represent seats which voted heavily leave,” he said. “We are trying to construct at the moment a traditional British compromise and we are trying to drag as many with us as possible both in government and elsewhere around some key elements of that compromise.”

Caroline Flint, a Labour remainer whose Don Valley constituency voted more than two to one to leave, defended her constituents, who she said had been insulted “day in and day out by some of the comments in this place and outside” stressing that they “are not against all migration”.

We need to address working class discontent but we do​​ not take the first step to doing that by making the country poor Pat McFadden, former Europe minister

Flint said she could not support EEA membership because it would mean there would be no restriction on free movement.

She said her constituents “want to have a sense that we can turn the tap on and off when we choose. But also they want us to answer the question, why hasn’t Britain got the workforce it needs, why has social mobility stopped, why do we train fewer doctors than Holland or Ireland and why are these jobs dominated by those in the middle and upper classes so my constituents don’t get a look in?”

But the former Europe minister Pat McFadden said it would be “unwise and rash” to take the EEA, the one viable alternative to a Tory deal on Brexit, or no deal at all, off the table.

Backing the Lords amendment, he said: “We need to address working-class discontent but we do not take the first step to doing that by making the country poorer, to not get the wealth for public services, for housing, and for the better chance in life our working classes deserve.”

The former shadow home secretary Yvette Cooper, who chairs the home affairs select committee, said she would obey the party whip and not vote for membership of the EEA only because she wanted to try to build consensus.

Cooper and Benn had introduced an amendment calling for EEA membership “with safeguards”. She said her committee had heard evidence about the measures other EU member states were applying to introduce some control over migration, which she had been told could allow the UK to have full single market access without complete free movement.

A spokesman for Corbyn said: “The Labour party respects the outcome of the EU referendum and does not support the EEA or Norway model as it is not the right option for Britain.”

• This article was amended on 14 June 2018. An earlier version said Laura Smith held the Crewe and Nantwich seat in the last election. Smith did not previously hold that seat, but took it in the election. Due to an error in the editing process we said Smith and five parliamentary aides had resigned from the shadow cabinet. They were not members of the shadow cabinet, and this reference has been removed.