Over 110,000 people have added their names to a petition urging the United Kingdom to seek membership of the European Union once more, pushing the total past the threshold at which Parliament is required to schedule a debate on the matter.

The petition, headed "Apply to Rejoin the EU as soon as possible to increase growth in the UK," calls on the government to pursue EU membership within ten years of the Brexit vote. Its text argues that doing so would lift trade barriers, support economic expansion, raise tax receipts, and restore opportunities for people in the UK. A Cabinet Office reply issued in January, shortly after the petition went live, indicated that ministers were focused on resetting the relationship with the EU. At the time of that statement's release, Andy Burnham had not yet taken office as prime minister.

A separate petition describing Brexit as failing to deliver on its promises has also attracted signatures. Burnham — delivering his opening address to the Labour Party conference as Prime Minister — told delegates that the UK's departure from the European Union had produced more negative outcomes than positive ones, and pledged to present the public with a range of options around the time of an upcoming UK-EU summit.

Lord Khan welcomed the British leader's characterisation of the 2016 referendum vote to Leave as a decision that had proven to be an error. A substantial majority of Londoners cast their ballots for Remain when the 2016 referendum took place, with 28 of the capital's 33 borough councils returning votes in support of remaining within the political and trading bloc.

Ten years on, survey data released during the summer pointed to public attachment to EU membership holding at levels comparable to those recorded before the vote.

Parliament reconvened on Monday following the conference recess. Among the earliest items on the agenda was a Westminster Hall debate — held in the secondary chamber used for non-binding discussions — centred on a public petition calling for the Brexit referendum result to be overturned.

Burnham has described himself as the first politician in Britain to openly assert that Russian interference played a part in the Brexit referendum outcome. In an interview set to broadcast on Monday, he put the question directly to those at Downing Street — had Russia played any part in shaping the outcome of the 2016 referendum?

Burnham stated that placing this on the record openly was, in his view, a matter of importance for voters in Germany and France — particularly given the growth in support for nationalist parties in both countries — so that people there could understand that some of the political activity they were witnessing had been set in motion by adversarial foreign actors, a conclusion he said he had now received a clear answer on.

He noted that the government had not done enough to keep the public informed about the extent of overseas attempts to interfere with domestic political processes. A 2020 report from Parliament's Intelligence and Security Committee concluded that ministers had not properly examined what influence Russian state media and coordinated online accounts might have exercised over the EU referendum outcome.

Lib Dem leader Sir Ed Davey acknowledged that he and Andy Burnham hold differing views on a range of matters, yet maintained that the kind of statement Burnham made was one a Prime Minister ought to have delivered. Choosing to go public marked a shift away from what some observers characterised as a pattern of restricted disclosure under Conservative-led administrations.

Burnham had raised the issue of Russian information operations a month earlier, addressing the UN General Assembly and noting at the time that available evidence pointed to Moscow having attempted to interfere in the 2019 general election. He called for considerably stronger action to safeguard democratic institutions from interference by hostile foreign states.