This week’s headlines will all be about the G20 summit in London and Gordon Brown’s efforts to forge international agreement on how to rebuild the international economy. But already the Prime Minister’s closest advisers will be preparing for a date in June that may have a more significant impact on Labour and the Government. The last real polls before the next general election will be held on June 4, when voters will chose their Euro MPs and take part in a small number of local elections. A low turnout is virtually assured as British voters once again show their customary indifference to the politics of the European Union. But the turnout figures will count for very little if, as seems likely, Labour is trounced at the polls. A heavy defeat will be a severe test of loyalty, even for the PrimeMinister’s closest allies. Mr Brown may respond with a reshuffle, with some of his most senior ministers, such as Jacqui Smith, the Home Secretary, looking particularly vulnerable. It will be his last opportunity to reshape the Government in the hope of restoring calm before what is likely to be a fractious summer recess, dominated by political intrigue and rumours of plots and counter-plots against his leadership. By then the G20 will seem but a distant memory.

By the end of this week Mr Brown will hope to have brokered an agreement at G20 that will commit the leaders of the world’s biggest economies to billions of pounds of state funds in fiscal packages that will help to stave off a global depression. However, there is a risk that the summit will expose the divisions that clearly exist over the best way forward, and that the final communique will fail to reassure investors. Thus London may well be remembered for all the wrong reasons. Throw in the threat of protests by an alliance of anti-globalisation and environmental campaigners and it easy to understand what is at stake for Mr Brown this week. Three weeks later, on April 22 , Alistair Darling delivers his Budget for 2009 and sets out the next stage of the Government’s plan for economic recovery. Rarely can a Chancellor have stood before the House of Commons with such a bleak outlook for the economy, with the public finances in disarray, a housing market in sharp decline, unemployment rising sharply and the manufacturing sector mired in recession. The focus will certainly be on short-term measures that will be proposed to kick-start the economy. But calculators will be working overtime as economists try to work out how many years it will take to restore the public finances to health, and at what cost to the taxpayer.

On the banking crisis, the Government’s record will come under scrutiny when the Treasury Select Committee publishes its report in April. After taking evidence from ministers, Treasury officials, the Bank of England and former directors of failed banks, the report will consider whether Mr Brown and Mr Darling did all they could to prevent an implosion of the sector and whether taxpayers have been exposed to excessive risk.

Within the Civil Service there is growing dissent over the extent of cuts that are being imposed on local councils as Westminster tries to balance the books. Unrest in the public sector over pay and job losses will be in evidence as teachers’ unions hold their annual conferences over the Easter period, and Unison, the largest public sector union, meets in Harrogate from April 20. Alan Johnson, the Health Secretary, who is a keynote speaker, should expect a frosty reception. In May the Police Federation of England and Wales will also voice concern over cuts in police numbers at its annual conference, pressing its claim that law and order is becoming a bigger social issue as the recessiontightens its grip. The latest annual crime statistics will be published on April 30.

Economic issues also complicate the debate over the environment, as pressure grows on Britain to reaffirm its commitment to reduce greenhouse gases before a summit in Copenhagen at the end of the year. By June, draft proposals indicating how reductions will be shared out will be put forward. Expect negotiations to be tough, with Britain facing awkward questions over the disappointing progress it has made so far. Scientists will hope to influence the debate in Britain during a Wave and Tidal Conference in Bath at the end of April to discuss the potential for sustainable power.

A successor to Cardinal Cormac Murphy- O’Connor as head of the Roman Catholic Church in England and Wales will shortly be named. After his retirement as Archbishop of Westminster, the Cardinal is expected to become the first Catholic bishop to sit in the House of Lords since the Reformation.

The 20th anniversary of the Hillsborough tragedy, when 96 Liverpool fans were crushed to death during an FA Cup semi-final against Nottingham Forest, will be marked on April 15. It will be a powerful opportunity for the game to take stock of how safety has changed in the two decades since the tragedy.