The row over Brexit and the Channel crossings is likely to become increasingly heated as ministers face renewed pressure to explain why thousands of people continue to make the dangerous journey from France to Britain.
For Mr Burnham, the argument is relatively straightforward. Leaving the European Union changed the UK’s relationship with neighbouring countries and removed some of the mechanisms that previously allowed British authorities to cooperate more closely with European partners. The Prime Minister’s suggestion is not that Brexit created the small boats crisis, but that it has made dealing with the problem more difficult.
That distinction is important because the Channel crossings developed into a major political crisis several years after the 2016 referendum. Small boat arrivals increased dramatically during the early 2020s, when Britain was already outside the EU. The Government therefore faces a difficult question: how much responsibility should Brexit carry for a crisis that has continued under successive governments?
Supporters of Mr Burnham’s position argue that modern migration enforcement depends heavily on international cooperation. Smuggling networks do not respect national borders, and criminal gangs operating in northern France can organise journeys whose final destination is Britain. Information about individuals, criminal networks, boats and financial transactions can therefore be valuable to authorities on both sides of the Channel.
Closer cooperation with France has consequently become one of the central elements of the Government’s strategy.
The £662million three-year agreement signed with France is intended to strengthen efforts to prevent small boats from departing French beaches. British ministers have argued that helping French authorities intercept launches before they leave is more effective than simply responding after boats enter British waters.
There is also an argument that Brexit has complicated arrangements for returning people who arrive in Britain after travelling through safe European countries. Critics of Brexit say Britain lost some of the advantages of EU-wide cooperation and now has to negotiate separate arrangements with individual governments.
However, opponents of the Prime Minister’s argument insist that this explanation risks becoming a political excuse.
Conservatives have argued that Britain had already struggled to return migrants to European countries under previous arrangements. They point to the fact that the number of people crossing the Channel remained substantial despite years of cooperation between Britain and France.
They also argue that the fundamental problem is not simply Britain’s relationship with the EU, but the incentives facing migrants and criminal gangs.
If people believe they can successfully reach Britain, lodge an asylum claim and remain in the country while their case is considered, critics argue, smugglers will continue to have a lucrative business model.
That is why the debate has increasingly moved beyond Brexit and towards the UK’s asylum system, deportation arrangements and international agreements.
Reform UK has taken the most uncompromising position, arguing that Britain needs much tougher measures to deter crossings. The party has called for stronger border controls and major changes to the legal framework surrounding asylum and deportation.
The Conservatives have also pushed for tougher action, with Chris Philp arguing that migrants who enter illegally should be removed rapidly.
Labour, meanwhile, has attempted to present a different approach. Ministers have stressed cooperation with France, action against organised criminal gangs and efforts to increase enforcement rather than making promises about an immediate end to crossings.
The Government has also been careful not to set a specific deadline for stopping the boats.
That reflects the difficulty of the problem. Even if British and French authorities significantly increase interceptions, the Channel is a large and busy stretch of water. Smuggling gangs can change departure points, launch times, boat sizes and routes in response to enforcement measures.
Recent events have demonstrated how quickly the situation can change.
More than 700 people arrived in Britain on a single day this week, while two boats reached British shores without being intercepted within a short period. Those incidents have provided fresh ammunition for opponents of the Government, who say that promises to tackle the crossings have not yet translated into sufficient results.
For ministers, however, the wider statistics provide a more complicated picture.
The overall number of arrivals so far this year remains below the corresponding figure from 2025. That gives the Government evidence that its approach may be having an effect, particularly when combined with increased cooperation with France.
But a reduction in the annual total does not necessarily end the political controversy.
For communities near the coast, individual incidents can have a disproportionate impact. Images of crowded dinghies arriving on British beaches quickly become national political stories. Every uncontrolled landing raises questions about whether the border is secure and whether the authorities know who is entering the country.
There is also a humanitarian dimension.
The Channel is one of the world’s busiest shipping lanes, and crossings in small, overcrowded boats can be extremely dangerous. People can die from drowning, hypothermia or accidents before reaching Britain. The Government therefore faces the difficult task of trying to prevent crossings while also responding to emergencies at sea.
Supporters of stronger enforcement argue that the safest policy is to make the crossings impossible to profit from. If smugglers cannot offer migrants a realistic prospect of reaching Britain, demand for their services should eventually fall.
Critics counter that shutting down one route does not necessarily eliminate migration pressure. People fleeing war, persecution or poverty may simply search for alternative routes, potentially creating new humanitarian risks.
That is why the political debate is unlikely to disappear regardless of the direction of the annual figures.
The Brexit question adds another layer to the dispute.
Those who supported leaving the EU can point to the fact that Britain now has greater freedom to design its own immigration and border policies. From that perspective, the Government should use the powers created by Brexit rather than argue that leaving the EU has made enforcement harder.
Those who opposed Brexit can make almost the opposite argument. They say that border security ultimately depends on cooperation, and that Britain’s departure from European structures removed some useful tools without eliminating the underlying need for cooperation.
The reality is likely to be more complicated than either side suggests.
Brexit may have changed Britain’s ability to cooperate with European countries, but it is difficult to argue that Brexit alone explains the rise in small boat crossings. Equally, it would be difficult to claim that Britain’s departure from the EU has had no effect whatsoever on migration enforcement.
The bigger question for voters may therefore be whether the Government is using every tool available to reduce the numbers.
That includes the agreement with France, intelligence-sharing, action against smuggling gangs, faster asylum decisions, effective deportations and international cooperation.
For Mr Burnham, the political risk is clear. If arrivals continue at high levels, opponents will argue that blaming Brexit is an attempt to shift responsibility away from the Government.
If the numbers continue to fall, Labour will be able to argue that its strategy is beginning to work.
Either way, the Channel crossings are likely to remain one of the defining political issues of the current Parliament.
And that leaves voters with a much broader question than simply whether Brexit is responsible.
Do you believe Brexit has made it harder for Britain to tackle the small boats crisis, or should the Government take full responsibility for solving the problem with the powers it already has? Vote in our poll and share your views in the comments.